I don't think it's common to use a mid-size longarm machine (13"-17" or so) on a tabletop frame. I think tabletops are generally used for domestic machines (maybe 9-11" harp size). If you haven't already, take a look at the Ken Lund tabletop frames on Youtube. His kits run around $175 to $255.
What is your price range? In general, if you go for a midarm or longarm machine you want to buy it at the same time as the frame to be sure they are compatible. It's often possible to find a used Voyager 17/Hinterberg stretch frame for under $3,000.
If you want to use a vintage Bernina 830, you need to be sure that the frame is strong enough to handle the weight of that machine.