I'd simply give Google AdWords a try to get started, there you'll be able to find traffic that's targeted enough to give a nice ROI, and volume wouldn't be a problem either if you're able to work with a lower ROI.
I agree with Ravo that buying skimmed traffic from any traffic source isn't a good idea, simply because it's thought as feeder traffic, and not to generate sales. But text links on TGPs / MGPs could work too, that's just a big trial & error game
