However, they then asked for $75, and I feel like their art is not worth 75 given their skill and quality. So, I asked for their public commission information and terms of service. They said they didn't have any.

So, at that point I felt like they were trying to take advantage of me, so I declined to commission them. They first responded in a joking manner, redirecting the topic. Finally ending with, "I understand, though it really hurts my feelings" :/

I then noted a few others that apparently got commissions from this guy.

One replied that indeed they were approached to commission this artist by the artist.

Without any public commissioning information, I'm thinking that this person hunts down people that often get art.