Getting multiple estimates is a good idea and it's free. I don't know any pond building pros in MD but maybe the forum can provide some recommendations. There is a great guy Drew Hays out of PA who travels anywhere for projects, but I don't think he's on the cheaper end. If you or someone you know can run a dozer and/or trackhoe renting the equipment for a few days would be the cheapest route.

Many men go fishing all of their lives without knowing that it is not fish they are after. ~ Henry David Thoreau

[Linked Image from i1261.photobucket.com]