The question was mostly rhetorical ;-) But I was just looking at consumer price indices actually. The Dept of Labor Bureau of Labor Statistics CPI Inflation Calculator suggests that $1 from 1970 has the same buying power as $5.19 today, so assuming shag carpets are no older than 1970 (as an earliest bound), apples should cost up to $0.78/lb or so now. Of course, I'm not taking into account regional or seasonal differences, fluctuations in apple supplies and pricing, or the fact that the prices in the movie could be from a few years earlier or even made up.