I believe that the common ground for the requests should be the interest for creating the map, not the cost. The price should be something settled by the parties depending on the complexities of the request, be it time constraints, detail, size or what ever. I also believe that it is withing human nature to want the most for the least, and having a list, no matter how it is presented, will only cause those that have no budget and wanting a simple map to look elsewhere. That is something that we should be avoiding. The filling of unpaid requests is a great way to practice working on a deadline and to someone else's specs (Another being the competitions.) and a great way to get into the field. Stating what you want to pay should only the opening salvo in the negotiations and THAT depends on the requester and should not be set by anyone else.

My two cents (+tax) worth.