If it is important to you that he likes the underwear, then my suggestion is to cash app him and have him buy the underwear himself.
A guy once showed up with 10 pairs of underwear for me to wear for him, and I did not like a single pair, so to avoid that happening to you, it’s best to just let him buy the underwear himself. And yes I think you should compensate him for the time it will take for him to do that.