A small server that exposes read-only tools over your product's data, such as search, look-ups and reports, is scoped as my AI Integration Starter package: $799 and one to two weeks. That covers tool design and the descriptions the model reads, test cases, integration with your API, usage logging, and documentation with a handoff call.
A server that can also act, creating, updating or assigning records, needs more care: sign-in tied to your existing accounts, permissions checked per user and per role, a confirmation step before anything changes, and an audit log of every call. That is the AI Integration Professional package: $2,499 over three to five weeks, with two weeks of support after launch.
Hosting runs on your own account, and the model usage is paid by whoever runs the assistant, not by your server. If you would rather buy hours against an existing backlog, I bill $20 to $30 an hour.