Quick answer
The cheapest and most expensive proposals may be describing different products. Put them side by side against the same brief. Check what each includes for discovery, design, development, migration, testing, launch and support. Mark every feature as included, optional or excluded.
Practical scope
Ask how changes will be approved and charged. Review the milestone plan and what you will receive at each stage. Clarify ownership and access to the domain, hosting, code, design files and data. Request a demonstration of comparable work, plus the names or roles of the people who will deliver your project.
Pay attention to assumptions: “content supplied by client” and “third-party integration excluded” can materially change the final cost. Choose a proposal you understand and can verify, rather than relying on a headline price or a long list of technologies.
What to define before requesting proposals
- Included, optional and excluded requirements
- Assumptions, dependencies and client responsibilities
- Milestones, acceptance tests and payment points
- Ownership, warranty, support and recurring cost
Questions to ask service providers
- Who will deliver the work and what comparable work exists?
- How are changes approved, estimated and charged?
- What access and files are handed over at completion?
How to assess the answers
Normalise proposals against one scope before comparing price. The best proposal is understandable, testable and explicit about assumptions and ownership.
Related planning guides
Next step: Put these decisions into one project brief, then ask providers to respond to the same scope.