I strongly recommend that you consider one of the affiliate networks (CJ.com or one of the other big 4) to use for this type of thing. They all handle payments

I strongly recommend that you consider one of the affiliate networks (CJ.com or one of the other big 4) to use for this type of thing. They all handle payments and all of the other details automatically. All you have to do is keep some money in an escro account and be willing to absorb their fees. Generally they charge 20% on top of any affiliate payments.