There are lots of good used machines 'out there' right now as some quilters trade up. You just have to search for them.
Other than budget concerns how much room do you have. I have a HQ 16 I got used. Originally had an 6 ft homemade table. Then enlarged that to 10 1/2 ft long. The machine and table take up a total of 4 ft without including me working on it. Personally, if space were limited I'd go with the HQ Sweet 16 sitdown model.
ali