I have a Bernina, which is probably pricier than what you're looking for, but definitely check craigslist! Lots of people get frustrated and give up on their sergers, or don't know how to use them, and you can find some great bargains there.
I mostly use mine for seams on things I don't want to have to line and rolled hems on ruffles and skirts. It's also great for knits, but I don't do a ton of sewing with knits. If you only use it for quilting though, I'd back up the others suggestion of just using an overlock (zig zag) on your regular machine. GL!