Athlete Pricing
There are many factors that go into the rate an Athlete charges for brand deals - their audience size, their history as a player, the league they play in, and so much more. At OpenSponsorship, we have made this question easy for brands by implementing User-generated pricing. With this, the athlete or their agent places a rate for each type of deal on their profile which can act as a starting point for negotiation.
Alternatively, you can use the campaigns feature to state that you are willing to pay $X in exchange for a set of pre-determined deliverables. Then, Athletes can submit a proposal against that rate.