If the traffic was any good they would not be selling it so cheaply. So, what to do? I have two suggestions, depending on your budget.
1. Buy ad space on other sites. Even if they don't send massive quantities of traffic, at least you get the branding in. You can find places to buy ad space at
PimpsPromo.com
2. Find out where they are getting their traffic, and go to the source. How do you do that? Get the
T3Report. Pick a domain and learn whey they get their traffic, and find out where their sources get it.
For example, you could order a report on Playboy.com, discover their traffic sources and where their sources get their traffic.