Only a scoped proposal can tell you what a particular counterparty will pay. Company size, file count and public marketing ranges cannot establish a reliable standalone valuation.
Ask what creates usefulness
Workflow completeness, permitted uses, rights, format and buyer demand affect the assessment. Some archives are unsuitable even when large.
Normalize proposals
Compare the same scope and account for exclusivity, deductions, payment conditions and preparation costs. A larger headline amount may buy materially broader rights.
What to record before deciding
Keep the written scope, official provider source, unresolved questions and the person responsible for each check. Treat a marketing claim as a claim until it is reflected in the agreement. A directory entry does not approve the transaction or establish your rights to share the records.