the artist in question, IrkinGIR, has been in that fetish "community" for awhile and has a good amount of clout, probably how he got away with charging so much.
More fucked up is, usually his art isn't that bad. It's not amazing, and certainly not worth $300 even when he's putting in the effort, but you can tell he COMPLETELY phoned this one in, with how lumpy and flat they look. Like it's laughably bad compared to his other shit.
Somehow, the commissioner was satisfied though. They have a huge gallery of niche fetish shit they commissioned, some of it very high quality, so I can only assume they're fucking loaded.