I think some of the DIY type quilting machines are actually re-purposed commercial sewing machines like for sewing draperies, sails, tents, etc. The motor is then re-mounted under the machine somehow or sitting on a little pedestal off to one side or even behind it. Tacsew, Consew, Singer, Tajima, Juki, Toyota and I don't know who else but I'm sure there are many more commercial sewing machine manufacturers make long throated, high speed, single or perhaps simple zigzag stitch machines. These machines are expensive when they are brand new/lightly used but you will occasionally stumble across one that has been stored for a while and the seller has no idea how expensive it really was. I think the NuStyle Quilting machines are re-purposed commercial Juki's or Consews.