Don't be afraid to ask about previously owned machines. If they offer a warranty, you can't go wrong.
I purchased a used Brother PQ1500 used for $400, which is about half of normal retail. You can usually find it on sale for $599 or $699. It is an awesome machine. Straight stitch only, knee lift, auto thread cutter, 1500 spm, 9" harp, needle threader, extension table, and it is mechanical. I bought it 5 or 6 years ago and haven't had a single problem with it.