What size audience would content creators need to match if they are going to be affiliates for me?

I've got a t shirt store with t shirts for CS GO, and I'm contacting streamers to be affiliates. The problem is that they want me to send them a free shirt, which is obviously understandable. For every shirt I send out for free, it'll take roughly 3 shirts sold to their followers that would refund me for the shirt before I start making a profit.

I'm just a little lost as to how much I should be sending out. 3 shirts doesn't seem like too much, but I've haven't actually sold any shirts yet, so I'm probably overestimating how easy it is to sell these.

I don't want to spend too much money into sending out free shirts that don't bring in any revenue, but I know that I'll never make any money if I don't spend any.

What size streamers should I send to? Big ones obviously have better sponsorships, but small streamers don't have as big a following.

Anyone who answers any of my questions, thanks in advance.

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