another suggestion coming from me to head over to your Sears store. i got my Janome there several years ago (they've since quit carrying Janome because they make Kenmore now). they were very helpful and i've been tickled! my other older machine is a Kenmore. it's a real workhorse!
if you can afford a little more, aim high on the options. if you've just started quilting, there will be things you will want to do as you get more comfortable with it. so pay a little more and get more machine than you think you'll currently use.
features you'll want to consider -
needle threader
up/down needle button
speed setting (the 'turtle' option mentioned above)
even feed foot
free motion quilting foot (sometimes called 'darning' foot)
1/4" foot
some decorative stitches
extra bobbins (sewing machines are very picky about their bobbins)
i think buttonholers are pretty standard these days
have fun picking out your machine!