I am trying to make a bidding site alot like ebay but i dont want to use ebay do to the huge charge they do. I am trying to set up something for home schoolers who can afford to pay alot to be able to get the school stuff they need and when they are done with the grade their child is in they can put it on my site and other people who will need that grade can bid on it. Does anyone know what kind of code i should use PHP or something else or if there is a software out there that will do it for me and all i have to do is fill in the blanks. thank you.

I don't want to deter you from what you want to do, but... Making a competitor to eBay is going to be extremely hard, your system has to be easier to use than eBay, and as secure. There's a lot to think about when writing auction software.

As far as the language goes, I don't think PHP is recommended, most major web apps are now either ASP.NET, Python, Perl, or Ruby on Rails.

im not making a competitor of ebay this is for a group of people that cannot afford ebay and its strictly for one product.

secondly i would rather not write the program i would like one that i could use already made like os commerce just easier and with the option to bid

You might take a look at PHPAuction; they appear to have a free version available.