I'm with kwendt - if you're looking for a machine that will "cut it" for piecing and quilting, you can't beat a 15-91 (or even the belt driven version, which I think is the 15-90, but I sometimes get the different flavors of 15 mixed up) The belt driven version has plenty of power for quilting tasks, including sewing on the binding and quilting over very thick seams.
You can find them on craigslist really cheap, and even by the time you've replaced all the electrical components and had the motor re-wired by a pro, (about $110-120, all together) you've spent less than it costs for a plastic machine that won't last you two years.
Some models of Kenmores from the 70's are just as wonderful and most will be capable not only of FMQ, but zig-zag utility and decorative stitches, monograms, buttonholes, machine applique - all kinds of stuff. I would recommend the 1802 and 1803, although there are many models of this basic machine that are only slightly different. (1702, 1703, 1940, etc) All of them will be as heavy as tanks and having it in a cabinet will make wrestling with a large quilt much easier. :)
Cleaning and refurbishing the old machines turns into a hobby of its own - it's a lot of fun and so rewarding to take a noisy, barely-turning hulk into a quilting machine. :)