When clients request an expert, make it compulsory that they include their budget or per hour rate for the project.
I get the impression that many clients are looking for something for nothing. Inclusion of a budget in their request should weed out those who are not serious.
Currently each inquiry indicates if the Client has a budget, we will consider asking for the budget amount but that might be information the client is not willing to share.
This would smoke out the "I want something for nothing clients". It would save client and expert time if the client can provides a rate per hour or indicate an acceptable range for rate per hour. I do not work for free.
If they are not willing to reveal their budget, they should not have same qualms about revealing a rate per hour they are prepared to pay. If they will not reveal this, they should be blocked. Likewise if they state a rate they are prepared to pay, but fail to follow through for this reason (cost) alone, they should be blocked from future requests for a certain period to be determined.