http://schwinncruisers.com/catalogs/1980.html Run these prices through an inflation calculator.http://www.bls.gov/data/inflation_calculator.htm The sort of bike a regular guy might have bought for fun and fitness would have been something like a World Sport, Traveler, LeTour, or Super LeTour. Varsity would have been more entry level, and very heavy. (37 lbs!) Anyhow, a 1980 Varsity retailed for $190, the Traveler, $195, the LeTour, $235, and the Super LeTour for almost $300. Calculate 1980 dollars to 2013 and you get anywhere from the mid $500s for a Varsity to $850 for a Super LeTour.
As for buying used, spend some time here, or on bike blogs, and educate yourself about what is good and what isn't.