Six factors explain most of the spread between a $1,500 quote and a $15,000 quote for the same company. The table summarizes them, and each is explained below.
Platform coverage
Optimizing for one engine is a different job than optimizing for five. Each engine selects sources differently, so every added platform means more prompt testing, more monitoring, and sometimes different content formats. The effect shows up directly in tool pricing: Profound charges $99 per month to track ChatGPT alone and $399 to track three engines, and agency retainers scale the same way once analyst time is attached [7]. Before judging any quote as high or low, check how many engines it actually covers.
Content production volume
Content is the largest recurring line item in most retainers. The common mid-tier package pairs ongoing schema management and prompt testing with four to six new optimized pieces per month at $2,500 to $5,000 [4]. Doubling output roughly doubles the writing, review, and optimization hours, so ask any vendor to state the monthly content count in the contract instead of describing it loosely.
Site size and technical scope
A 15-page site and a 500-page site need very different technical effort. Large-scale schema deployment, answer-block restructuring across templates, and weekly citation audits push enterprise site retainers to $5,000 to $10,000 per month even before net-new content [4]. When comparing quotes, confirm how many pages each vendor actually plans to touch.
Off-site citation building
AI engines cite sources they trust, and getting your brand into those sources requires outreach, digital PR, and original research that AI models find worth referencing. OutreachBloom describes citation building as the expense that "eats the budget" in agency retainers [3]. Published price lists reflect the same split: Lean Labs prices its off-site authority program at $7,000 per month against $5,000 for on-site work [11]. Quotes without any off-site component should be meaningfully cheaper.
Industry complexity
Healthcare, finance, legal, and deeply technical B2B categories cost more to serve because every claim needs editorial validation, data verification, and often subject-matter review before publication [5]. Vendors also price for buyer-journey complexity: a considered B2B purchase requires more content across more question types than a simple local service [5].
Provider type
Who does the work moves the price as much as the work itself. In the closest surveyed market, agencies charged 138% more than freelancers on average [9], and the same gap shows up in AEO: freelance retainers run $1,500 to $4,000 per month while agency retainers for the same company size start around $2,000 and climb past $10,000 [4][2]. Agencies bundle strategy, production, and reporting under one contract; freelancers usually cover a narrower slice at a lower rate.