Best ad network that targets MMORPG website for $1k-$5k buy?

Hey all,

I just ran the stats on a product that I sell online for World of Warcraft gamers and have noticed that my overall eCPM is pretty insane. I currently advertise on a small number of sites and have seen the eCPMs I earn are between $13 and $70 and I'm only paying around $2 CPM, so my profits are insane. The past few weeks I'm seeing 25x multiplier on the money I spend vs money I take in.

The problem is, the sites I advertise on now aren't very big, and I've got them booked 100%. I would like to try out advertising on an ad network, something that has the specific World of Warcraft audience.

Does anybody have any idea what ad network to use, and if they could do a $1000-$5000 test campaign to see the results? The big ad networks only seem to be interested in test campaigns $50k in size. I am interested in that, but not quite at the moment.

However, if the results were the same as they are now, imagine spending $50k on a 25x multiplier...

Thanks in advance for your feedback!

(note: Posting now in ad forum, accidentally put it in general forum before)