I agree with many of the above comments to "test drive" several models and also it helps if someone in your area can teach you its use and service it if needed. I also want to comment about your room. Make sure you have enough space. You'll need to be able to get around the entire machine and frame. Also look at how the "sandwich" is applied and held on the frame, how do the rollers advance, how easy is it to adjust the height of the frame. Is the machine upgradeable (sp?)? If you spend less money now, can you add features later?
Bottom line is LOTS of HOMEWORK and research. But afterall, this is a large investment and you don't want to spend your money and then be dissatisfied.