Let's put it this way.

You will NOT find a single top-selling marketer online requiring their affiliates to purchase their product before they can promote it.

I can sell Marlon Sanders products all day long. But, Marlon doesn't require I buy his products. He may "suggest" that I do, but I'm not required to.

If I know the market you're trying to pitch to, and if I know how to promote effectively to that market, I don't need to buy your product in order to sell it.

I took a turn at selling cars many, many years ago. I didn't own one of the models, but I could sure sell 'em.

My personal opinion, if you do require your potential affiliates to buy before selling, you're shooting yourself in the foot.

My 2¢

Pete