Well, it's a Kenmore ZZ sewing machine. Probably a 158 series by the shape of it. Looking at the controls I'd say the machine has a built in button hole stitch in addition to the SS and ZZ stitches.
It has a feed dog drop knob for FMQ as well.
Nice machine. I might try to get the seller down to $40, but I wouldn't go down to $30. Just me.
Joe