Whatever you get, I would highly recommend one that has infinitely variable stitch width and stitch length adjustments. If you ever get into invisible machine applique, you will thank me for that recommendation! Basically it just means that you have a dial available to adjust width in as small an increment as you want, and another dial available to adjust stitch length in as small an increment as you want. Avoid machine that give you fixed stitches with unadjustable length and width.
Needle-down is a feature that most quilters really like, but I don't think you can get it in your price range.
You might be able to get some needle positions, though -- meaning you can adjust the needle to the left or right of center.
I'd probably go to Sears for the type of machine you are looking for.