I also love the Singers no matter what anyone says. The last one I bought last year is the Singer Quantum L-500 which is awesome. It retails for around $1700 in some retail stores but picked my up from internetsalesusa.com for $728. I saw just last week where the same place had it for $668 or so. Less than $700 and that was with free shipping. It is smooth sewing, no loud noises, is heavy duty (not a machine you would just pick up and move around to often) has serveral computerized stitches, can wind bobbin while sewing, has dual feed and more. You will not be disappointed. It also came with a bunch of feet.
I also bought the computerized Singer Featherweight 75 over a year ago to carry with me to sew sessions and such and that also is a work horse and this one has more computerized stitches than the one mentioned above.
Despite what folks say I would not go for another more expensive brand.
Lets face it all brands now belong under an umbrella of one corporation for the most part. They simply put a different name brand on a machine for the most part.
Even though it's over your $500 budget you may want to still look at it and consider this one.