You can get aftermarket foot controls for it easily and a 1/4" foot is commonly found too . (Sew-Classic.com) Use Tri-Flow for oil and tri-flow grease for the gears (not for the motor) and go to Singers web site and you can download a free manual with all the oil points listed. It's really a fairly easy keeper and it sounds like you got one that is pretty complete. Enjoy!
If you decide to sell, a "fair price" is market dependent so I'm not much help there but maybe someone from your area will chime in.