Under most scenarios this works fine. I think we're talking about one sequence of events:
- Client gives you a project.
- You do project and bill $2000
- Client decides to research tools used to accomplish the project
- Client finds tools at WA - not a problem
- Client also finds that a ready made solution is available for $1800 less
Now you're put in an uncomfortable position. The value of your other services are not the issue.
Just a point of view. Not suggesting anything else.