Just a thought though after reading your title - I think those in-house affiliate program - those that are offered by the company themselves, are probably better than those programs offered by the affiliate network.
The in-house affiliate network rarely offer recurring commissions, and they are so stringent with the affiliate rules that they monitor every thing on their network, which would cause issues when you start hitting $500 or more in commissions on their network.
Can't suggest any here, but you can look at some of those in-house ones, and their affiliate managers are usually very receptive.