I love finding old quilting books at thrift shops, and one of them talked about how to make your own basting frame, using 2x4's, clamps, and heavy fabric (like canvas).
The technique they used was first they wrap the fabric around the boards and tack it down so that there are a sort of "leader" left free; that fabric stays on the boards indefinitely. Clamp the four boards to each other in the proper size for the quilt backing, then pin the backing to the leaders all the way around all 4 sides, keeping the backing taut. So you're left with your backing fabric stretched between boards. Then they put that up on sawhorses, layered batting and the top, and then thread-basted. This was prep for machine quilting.
I think that's actually a pretty neat method, and the cool thing is that when you're done it all comes apart and you just have to store 4 long boards and some clamps somewhere.