Mine was from scratch. I designed and built it. It's made from MDF, some plastic and recycled linear rails and linear bearings. I had lots of help from info on the web.
Drive board and stepper motors were from
www.stepperworld.com
There is a fellow on the web who sells plans for home made cnc machines made from hardware store parts and hand tools. I didn't buy his plans but he had lots of good advice for me anyways. Very knowledgable on home made cnc.
www.crankorgan.com
Mine is 12" x 24" cutting area. Cost me about $300 USD not including the router, which was another $60.00 USD. Slides and bearings were free.
Eric