Why are you looking for a 20% commission? You do realize that 20% of $1 is $0.20, while 20% of $100 is $20... BIG difference there. As for PPC cost, I don't think anyone is giving away their secrets. Do the work yourself, and see...
Hey I suggest you to go to CJ Account manager and clicck Get Links and then choose the category of ur website or PPC Campaign.. then select one which has 20% Commission... its easy as CJ displays all in rows.... and then use Google adwords keywords tool to get the esitmate cost for keywords related then apply for that program... It will help you... Good Luck
But, 5% of $1 is $0.05 and 5% of $100 is $5. : ) As for secrets and work, this is also a work isn't it?
If you want to go for big buck then go with hosting company. Most of them pay up to 100 for each sign up
You could look at advertisers that pay per lead, like credit card / financial products, mortgages and loans etc. but the PPC market is hyper-competitive. If you want to find high commissions you need to look for high margin products.