Keep in mind Affiliate Networks are businesses, they only make money if you send them traffic. They can have all the offers in the world but without your traffic most of them ( that don't run mostly on their internal stuff ) would go belly up. So anything is negotiable because there's always another affiliate company. Hell probably 2 new ones start a week. For a very low investment you can start one yourself using Directtrack shared hosting it's peanuts. They need and want your business, work with them.