[RawAlex]

Anyone who has bought pay per click traffic knows that you are taking an inherent risk in this manner, because if it doesn't sell, you make nothing.

50% affiliate programs are a reasonable way to go. It balances the risk of sending traffic for the affiliate with the risk of not converting for the program. You work together to obtain the same goal (sales and long term members), instead of working against each other.

Flat pay (pay per signup) programs work in an adversarial way. The program bets they can keep the person longer, and the affiliate worries only about the immediate sell, regardless of what they have to promise in promotion to make it happen. The goals of the affiliate and the program don't match.

PPC ads? Same deal - the objective is to get the most clicks for the affiliate, regardless of the outcome. The programs goal is to create advertising that isn't clicked by anyone who isn't a serious buyer. You are not working together.

Lisa has it figured out. It is easier and more lucrative to crowd source your traffic then it is to spend your time on it directly. It isn't that you shouldn't ALSO work your own traffic sources, but wide distribution and exposure comes with an affiliate system.