Custom PHP Script

I’m looking for a customizable classified close too www.scriptdevelopers.com. I've bought a script from them but unfortunately they are out of business. I'm willing to buy a script like it, but I need a web coder who can customize a few things to my liking... (add percentage fee, feedback, change fields, listing fees, “make an offer” ability, buy it now, buy it later...,papal, merchant, ect.). But before I buy a script I need to know what kind of script the coder can work with. I want to finish this project within a month. Preferable php. In your bid, please specify what is the right software package that fits my needs or whether you are thinking of doing it from scratch.