I've got a deep rock rig. Drilled my own, and five other wells, to pay for the rig, and make some easy cash. Water table is 80 to 120' deep, rarely any rock beds. If I hit rock, I pull out, move over and start again. Make my own bits, weld hardened steel on the homemade bits, and add carbide to the edges.
Yes, you could consider it junk. BUT, it did what I wanted it to. You get what you pay for. Cost 1/3 of what the driller would've charged me. Successful drillings, and still have the rig and parts. Didn't want a 50k rig, that might take a tad bit more work to pay it off, plus getting permits, which I avoid if at all possible.
I wasn't trying to get rich, drilled for friends, neighbor, and parents. Parents got off scot free, others I gave a base rate of $100 for showing up, and would work until I hit water that suited them. If it produced, $200/day extra to completion. I gave them wells for under $500. Neighbor had a pro drill a deep well for $5000, but the water had too much sulfur in it, was killing his Christmas trees he raises. He was more than happy to have an unlimited sweet water well for 500$.