A cheap PPC agency can become very expensive when it protects its fee by protecting spend, not profit. That is why PPC agency pricing models deserve more scrutiny than a headline monthly quote. For an established eCommerce brand, the right structure should reward disciplined growth, give you clear visibility of costs and keep the agency focused on commercial outcomes rather than clicks.
The question is not simply, “What does an agency charge?” It is whether its commercial incentives match yours. If your target is profitable scale, the agency should be working from your margin, breakeven cost of sale, stock position and repeat-purchase economics. A pricing model cannot replace capable account management, but it can reveal a great deal about how an agency thinks.
The Main PPC Agency Pricing Models
Most agencies use one model or a combination of several. None is automatically right or wrong. The best fit depends on your ad spend, complexity, growth stage and the work needed beyond campaign adjustments.
Percentage of ad spend
This is the most common arrangement. The agency charges a set percentage of the monthly media budget, often with a minimum fee. As spend rises, its fee rises too.
The advantage is simplicity. A brand spending £10,000 per month and one spending £100,000 do not demand the same level of analysis, testing, reporting, feed work or strategic oversight. A percentage-based fee can also make it easier for an agency to resource an account properly as it grows.
The obvious concern is misalignment. If an agency earns more when spend increases, it may be tempted to push budget before the account can sustain it profitably. That does not mean percentage pricing is flawed. It means the agency must be judged on how it manages efficiency while scaling. Ask whether it sets a target ROAS or cost-of-sale range, how it handles declining marginal returns and whether it will recommend reducing spend when profitability demands it.
For many established eCommerce brands, a percentage of spend works well when it is paired with a sensible minimum and clear performance expectations. The percentage should not be the only conversation.
Fixed monthly retainers
A fixed retainer means you pay the same management fee each month, regardless of spend. It creates predictable costs and can remove the concern that an agency is simply chasing a bigger media budget.
This can suit brands with stable spend, a defined account structure and a clear scope of work. It is also often sensible where feed optimisation, Shopping strategy, Performance Max management, creative feedback and landing-page insight are central to the brief. These activities matter to revenue but are not neatly tied to a single month’s ad spend.
The trade-off is capacity. If you double your budget, expand into new markets, launch hundreds of products or require intensive creative testing, the original fee may no longer cover the work properly. A strong fixed-fee agreement should state what happens when the account materially changes. If the scope is vague, either side can end up disappointed.
Performance-based pricing
Performance pricing links the agency fee to an agreed result, such as revenue growth, ROAS, cost of sale or profit contribution. On paper, this looks like the purest form of alignment. In reality, it is the easiest model to oversimplify.
Advertising performance is affected by product pricing, stock availability, conversion rate, promotions, site speed, competitors, seasonality and attribution settings. An agency can improve campaign quality, but it does not control every variable that influences revenue. A performance-only deal can also encourage short-term decisions, such as prioritising branded search or remarketing because those channels look efficient in platform reporting.
For a performance arrangement to work, the baseline must be credible and the data must be trusted. Both sides need to agree which revenue is included, how refunds are treated, whether VAT is excluded, how brand activity is accounted for and what happens during major promotions or stockouts. Most importantly, the target needs to reflect contribution margin, not an arbitrary ROAS number.
Performance pricing is usually strongest as part of a hybrid model rather than the entire fee. A base retainer funds the specialist work required to run the account properly, while a variable element rewards meaningful, profitable progress.
Hybrid fees
A hybrid structure combines a fixed fee with a percentage of spend, a performance bonus or both. For serious eCommerce advertisers, it is often the most balanced option.
The fixed portion gives the agency enough certainty to invest in the account: auditing search terms, restructuring Shopping campaigns, improving product data, analysing audience signals and testing creative angles. The variable portion recognises that a larger, more complex account requires more attention and that strong results should be rewarded.
The detail matters. A hybrid fee should not become a confusing set of add-ons that makes your true cost impossible to calculate. You should be able to model the fee at current spend, at your next growth milestone and during a quieter trading period. Transparency is part of accountability.
Tiered pricing and project work
Some agencies use spend bands, such as one fee up to £20,000 in monthly spend and another above it. This is a practical version of percentage pricing that avoids small month-to-month fluctuations. It can be helpful for brands with seasonal trading patterns or planned budget jumps.
Project fees are different. They are commonly used for account audits, tracking repairs, feed rebuilds, campaign migrations or a defined launch plan. A project should have a clear output, timescale and handover. It should not be used to disguise ongoing management as a one-off piece of work.
How to Compare Pricing Without Being Misled
The lowest fee is not necessarily the lowest total cost. A manager who misses wasted spend, leaves broken feed attributes unresolved or reports only platform revenue can cost far more than the difference between two retainers.
Start with what is actually included. Does the fee cover Google Ads, Google Shopping, Performance Max and paid social, or are channels charged separately? Is feed optimisation included? Who monitors search-query waste? How often are creative, audience and product-level decisions reviewed? You are not buying access to an ad account. You are buying the judgement applied to it.
Next, assess the reporting standard. Revenue and ROAS are useful, but they are incomplete without margin context. If a product has a low margin, a 4x ROAS may still lose money after fulfilment, returns and overheads. A commercially minded agency will ask for the numbers needed to set realistic targets. If it promises a result before understanding your economics, treat that as a warning sign.
You should also clarify ownership. Your business should own the advertising accounts, product feed, conversion tracking and historical data. An agency relationship should be easy to assess and easy to leave if it is not working. No long-term contract is only valuable when the agency earns continued trust through performance and clear communication.
Choose a Model That Supports the Next Stage of Growth
A smaller brand with a straightforward catalogue may benefit from a fixed fee while it builds reliable data. A larger retailer managing thousands of SKUs, multiple campaigns and significant monthly spend may need a hybrid arrangement that funds deeper operational work. If profitability is already proven and measurement is clean, a performance component can add useful accountability.
Avoid choosing a structure solely because it appears risk-free. An agency charging only for performance may set cautious targets or focus on the easiest conversions. An agency charging only a percentage of spend may have less reason to challenge inefficient budget growth. The answer is not a perfect formula. It is a clear agreement between a capable specialist and a brand that knows what profitable growth looks like.
At Oxedent, the work starts with commercial reality: the products you sell, the margins available and the waste currently sitting in your paid media. Pricing should follow the same discipline. Before signing any agreement, ask how the model behaves when results improve, when they decline and when your business needs to pause. The agency’s answer will tell you more than the quote itself.