My experience with adbrite was awful as well. I've had the best success with AdWords and (gag) YSM. You can't just iframe an offer's landing page and expect to do well, though. Takes work and a good LP (read: testing) to get your quality score, CPC and conversion rate right. Still looking for an experienced PPC -> CPA arbitrage partner.
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The world's going to hell in a handbasket, but I'm selling the wicker.
I wouldn't have thought that Yahoo was a cheaper option. I am sure their minimum bid is $0.10 plus many people claim that they are earning on average over $0.50 per click.