when you buy a website, you are buying its domain name. Note that just because you bout a website, it could still have nothing on it after you bought it. So make sure you are getting all the content and offers. If not, you need to question, just how important is it to have that exact domain name. If you are going to use PPC, it may not be that important.
If the site is positioned as #1 or #2 in Google Search result pages and their is lots of monthy traffic to the site and the offers that are on the site can be transferred to you, than it might be worth it.