I did lots of research and I would highly recommend
http://sewing.patternreview.com/SewingMachine/Reviews for sewing machine reviews. They list the good, the great, the bad and of course the ugly. I have an Elna 2600 through a dealer you can buy it between $250 and $500 depending on the day and the sale. I love this little machine. It would and has worked it's self nearly to death (death wouldn't be even on the horizon if UPS hadn't dropped my poor machine). And even with all that I can still convince it to work for me.
Any sewing machine you think you might be interested in you can plug into that website they are listed by Brand and then by date, so you do have to sort through the list, but they also so a price paid, so you'll know if you're in the proper price range.
Don't forget to think about what you need and what in a sewing machine. Do you want to be able to use your old sewing machine feet for instance? Perhaps you would prefer electronic over mechincal? Are a lot of stitches important or do you prefer to have length and width control?