First, I spent a reasonable sum for a 3D printed conversion kit for a subject that I "had to have", the kit came in, and was nice, IMO, but will need a significant amount of work to the body in order to make it smooth and what I would consider paintable. To me, that is OK, as this is a subject that I do not believe we will ever see in kit form.
Example number two, was an engine and transkit that I purchased from Texas 3D Customs. It is an amazing piece, period, clearly this guy has done his home work, has experience with Blender, or whatever software he is using to get the file ready for print, and I plan to give him more of my money, it is as nice or nicer than any styrene or regular cast resin part I have ever purchased. I would say in line with the likes of Modelhaus or Replicas and Miniatures.
Finally, I ordered from a third vendor, and the parts looked like they were layered sheets of resin, and would take waaayyyy more work then I am interested in putting into a modeling project. This is my hobby for fun, I "work" enough during the day....LOL
That being said, I believe, that 3D Printing is the future of our hobby, you should see some of the work Bill Geary is doing with his gear.
I plan on getting a printer for myself at some point, when I can commit enough time to get quality prints.