Even some parts can often be more than you think, especially if your programmer writes decent php code.
For example, a friend of mine took me on for a small job recently, for £75 (which i can thank god repay my parents with
finally). It sounded easy, then when i thought about it and saw what needed to be done, i realised it was around a 3000 line odd system, and a similar 3-4000 line admin CP. ALOT of code.
Also, many PHP programmers will often be busy with studies, or maybe jobs for paying customers. I think you're best bet would be to take a look at the PHP langauge and see what you can do yourself. The forum members will always be happy to help out with code and programming problems.