This site is more for helping people with specific PHP programming problems than it is for supplying complete, ready-to-use applications. (Also, it is against site policies to solicit for or offer employment, so offering to pay someone here is not kosher.)
My recommendation would be to search sites such as sourceforge.net, hostscripts.com, etc. for a ready-made script. If you don't find anything, then look for sites where developers offer their services for pay. And of course, another option would be to spend some time learning PHP and MySQL, and then build it yourself (with help from PHPBuilder.com when you have specific, focused questions for us to help you with).
