$2 and 2% here and there is not extra income. Affiliate programs so low are insults to your hard work and are distroying the affiliate market. Even if you refer people they only pay you at they're sole discretion. If you still want to work for pennies on the dollar, at least make sure the terms and conditions are in your favor.
If you want to make 20-30% like you should, the best way is to call the owner up and ask for it. It worked for me, plus they know you mean business when you speak to them one on one. And I agree Clickbank is an great program. They're not the best but are the most convenient and actually want to pay you. They are also great about giving you a refund if need be. I always shop through them.