There are 2 options. One, is plain old steam workshop, or 2. You can go to sfm labs and look up nsfw pony models

3. someone makes custom pony OCs for money?

Not sure about that one, but I’m sure there is one

The steam workshop probably has some, though if you're looking for NSFW models you'll have to look elsewhere. Pretty sure SFM labs has some anthro ones, though I'm not sure about the one's from the show, might need to settle for a SFW one or download the bits separate and splice em

i was told this pony creator website cannot port OCs to sfm
http://ponylumen.net/games/3d-pony-creator/#