I don’t think 50/50 is a fair split in most cases. On all my products I give anywhere between 55-75% to affiliates, depending on the product. Your right, the guy who has the list needs some incentive to pick you.

Plus, affiliates without lists probably have to pay for adverting, like AdWords or other means. A little extra compensation because they are incurring an out of pocket expense for adverting your product. I would suspect this is also fair.