It can be tricky to find DeLoreans for sale, and I don't recommend buying one off eBay unless you love to gamble. Here are some sites that I frequented in my search for the car:
Hemmings Classic Car classifieds always returned the most results in DeLorean searches.
You can use the "search all Craigslist" sites, but you will also get a lot of junk you probably don't want, like DeLorean toy cars, etc.
DMC has a page on their website of cars for sale, but don't expect to find any deals here. I suggest calling the DMC location near you and asking if they have, or know of any, cars for sale in your price range.
There's a Facebook page for DeLoreans and spare parts. You'll have to request to be added.