Just a small bit of advice...you get what you pay for. You are looking for a good web designer...not only that, you need a talented web programmer. In the scope and scale, the project you are looking at should bid for quite a bit. Do you have 10 or 20 grand you are willing to drop? If so, I know quite a few developers that I can refer you to.

And some general advice to go along with it....you want cheap, fast, and good, and it is only ever possible to get up to two of those at a time.