Bidding Site For Car mechanics

Thanks for taking time out to read my project. I would like to have a bidding site similar to freelancer. There are several scripts out there: [login to view URL] has a nice freelancer script -[login to view URL] also has a nice one. I'm not sure if it will be more efficient if you know where to get a good script or if one of the mentioned will work. This site is going to be specifiaclly for car mechanics and car maintanence. There will only be 6 categories: brakes and tires engine work electrical paint & body diagnosis other The landing page should allow the visitor to see all projects and browse categories and log in or sign up. Its similar to freelancer. Its going to be FREE for mechanics and customers. Free for everybody, SO, tell me if you would like to build your own script or use one of these and customize it.