I have a Bernina 440 QE and got it used for a good price. That said, it was over $800, but you might be able to find a dealer with a good buy on a used lower end model Bernina. They come with wonderful warranties.
I have heard there is a starter janome out there for about $400 new but don't know what it does stitch wise. There are a lot of good quality machines out there, but your best bet is to find a dealer nearby and try them out. In addition, having a shop nearby is vital as service after the sale is soooo important.
Good Luck!