If you're concerned about cost and quality at the same time definitely talk to the folks over at TabooRevenue.
Taboo Dude posted this link:
http://www.trackingsoft.com/newroia.pdf
The page may be a bit intimidating but if you'll hit one of the ladies up on ICQ or Email they are fantastic to work with and also promote the hell out of your program for you. So you actually get marketing services wrapped into that deal. It's affordable enough that a very very small operation can use them successfully.