The cost of SEO depends on the problem, the site and the amount of specialist work needed. We scope engagements after understanding those variables rather than publishing packages that pretend every business is the same.
Site size, platform complexity, technical debt, competitive intensity, content needs, geographic coverage and the support available from your team all affect scope.
An audit suits a defined diagnostic problem. A project fits migrations or architecture work. Ongoing support fits programmes requiring continued content, technical and authority work. The right model follows the work.
Ask how priorities are chosen, who completes the work, what access is needed, how implementation is supported, how progress is measured and which assumptions could change the scope.