I was going stir crazy at home, so I decided to go out to Value Village. I found a Super Nintendo with hookups, two controllers, and beat up copy of Yoshi's Island for $24.99. I eagerly snatched it up, because around here that is a bargain! (My local shops are selling SNES systems for $40 to $60 without a game.)
However, after talking with a local shop owner, I discovered there was something broken on my SNES. There is a round piece of plastic missing from back of the system where the power adapter plugs in, but the metal pins are still there. I gave it a test run anyway, and amazingly enough it still works! I played Yoshi's Island for while and I didn't have any problems.
The shop owner said that as long as I am careful with SNES's power adapter (e.g. don't bend the pins), it should work for a long time. Although, I am curious whether there is a way to fix/replace that missing piece of plastic.