Depends on how much that amount is VS the quality of the work presented.
You should definitely pay something since you just admitted to having received his work on a public forum. Else you could potentially open yourself up to lawsuits.
I’m some states a verbal contract is binding.
In others it’s only binding in some circumstances (like age)
Regardless, you’d be an ■■■ to commission work, receive it at whatever quality and not remit at least some payment.
Maybe make it as an incentive.
Pay 25% so he can walk away if he wants to.
Define better parameters he needs to reach to get 50%, and what quality you expect for 100%.
OBVIOUSLY if your full amount was less than $2k usd just pay the poor soul.
And expect to pay a lot more for quality