Flat fee vs percentage of ad spend: what a $100K a month brand actually pays

What does each pricing model cost at $100K and at $1M a month?

A worked example. We assume ad spend of 10 to 15% of sales, in line with Marketplace Pulse's finding that a typical seller puts up to 15% of revenue into advertising and promotions (seller P&L sample, 2023). Rates are the published ranges in our Amazon agency cost guide.

Why does percentage-of-ad-spend pricing create a conflict?

Because the agency is paid more when you spend more. Raising budgets is sometimes right, but on percentage pricing the person recommending the increase also earns from it, and you cannot tell from the outside which of the two motives is speaking.

A flat fee removes that question. The only way a flat-fee agency keeps the account is by growing profit, so the conversation stays on TACoS, margin and organic rank, not on spend.

When is a percentage fee the better deal?

When the account is small and ad spend is low, a percentage of a small number can be cheaper than any flat retainer. That is why entry-level brands often start on percentage pricing.

It stops being the better deal as you scale. For a brand already doing $100K a month and aiming for $1M, the percentage model becomes the most expensive line item an agency can hand you, and it gets more expensive every month you succeed.

What should a flat fee include?

A flat fee is only good value if the scope is complete. Ask for these in writing:

• PPC management across Sponsored Products, Brands and Display, with weekly optimization.
• Listing copy, images, A+ Content and Brand Store updates without extra invoices.
• Catalog and account-health work, including cases with Amazon.
• A named account manager and a monthly strategy call.
• Notice period and any setup fee, before you sign.

Shaazford's $1,600 plan includes all five: account manager, designers, video editors and developers, month to month with no setup fee: cancel at least 10 days before your next billing date and you are not charged again.

How do you compare two agency quotes fairly?

1. Convert to a monthly number. Use your current ad spend and sales to turn every percentage into dollars.
2. Project it at 2x and 5x. If your plan is to grow, price the agency at the size you want to be.
3. Add the extras. Setup fees, creative invoices, minimum terms and exit penalties.
4. Check who does the work. Ask for the people on your account, not the people on the sales call.
5. Ask for named results at your size. A brand doing $100K a month needs proof from brands at that stage.