I suppose it depends on what condition a Penney is in that determines its worth. The (JC) Penney pictured below is hopefully worth more than a penny. It is a model 6940A. Cast aluminum body so it is nice and light, mostly steel parts inside, save for the stitch cams and a gear or two, and a handy carrying handle on top. All in all, it is a fairly nice machine.
As can be seen, it is a free arm machine. It takes low shank feet, standard Class 15 bobbins, and the needle flat goes to the rear. The motor is .78 amps but the machine has a step-down pulley system to provide more torque. I didn't notice it stitched any slower than my other machines so maybe the motor spins at a higher RPM.
Below are most of the stitches it can do. I ran out of room to fit all of them on the square.
When I do buttonholes on these sample squares, I usually use a buttonhole foot, the kind that has a fixed center and a sliding outer rectangular ring. The buttonholes seem to come out soooo much better that way.
Here are photos of the rear and side.
Funny thing, I just googled this model and found that someone sold one on a popular auction site for over $350 back in 2011... I had no idea the gold mine I have in front of me... Maybe...