My Sears bike is nice enough for a daily rider... I have updated to alloy rims and a cotterless crank, Nitto stem and alloy bars.

If it is the right size, I would say almost any bike is worth $20.

Mine was all original when I got it from the original owner, a good friend of mine, and it didn't have wing nuts in the back. It did have them in front, and it had Shimano derailleurs. I found my bike in an image of a Sears catalog, and it was Sears Finest 10 speed in 1971... The one you saw sounds similar, only possibly a different year.

http://www.aperfectworld.org/Other_P...s/sears195.jpg

Interestingly, it seems that each Sears model came in only one size. Their best came in 22" at least in 1971.