Classifieds/Personals PHP website

I'm planning to open a classifieds/personals website, and I want to compare prices between ready-made scripts available on the web and a script that would be made specially for me. I need all functionalities offered by any classifieds site (ask me for details if needed) such as free zone + paying zone/subscription, but also need full possibility of "customization" and so use the script in a wide variety of possible situations (general multi-categories classifieds, matchmaking/dating website, penpals website etc ...). If possible, no ZendOptimizer.