You definitely did not get ripped off, that's a cool old bike. You'll never get more than $50 for it unless someone's a collector or had one as a kid or something, you should just enjoy it!
I disagree with ^^^
I've seen similar bikes in similar condition go for 3 or 4 times more than that!
It all looks very and clean and has got some nice bits on it, can you get some closer pics of some of the parts? (like stem, pedals, bars, brakes, wheels etc) Then i'll be able to give you a better idea of pricing!