Freebie would be good, as it doesn't exclude anybody. But I see where you're going with the reward for purchasers of your store. It's a tough call really. I say go for what you feel best. You spent time on this, and it's up to you on how you want to distribute it. How about releasing it to purchasers, and if there's enough demand, then release it free for all? I must say though, that's a damn killer texture. Instant recognizability (if that's even a word) for the character it's based on. How about more in the series? :)