You can't do a straight dollars to dollars CPI calculation. Remember that the Italian lire was incredibly weak vs. the dollar back then. Now the Euro is stronger than the dollar and shipping, as you international buyers and sellers know, is really expensive.
Remember Frommer's "Europe on $10 a Day"? ...1977. I think the last version was "Europe on $85 Dollars a Day" in 2004. That would be $100 now, for sure.
So, if 10x is the right multiplier, then your $500 Colnago back in the day is $5k now.
Julian Shapiro
in relatively balmy Sag Harbor, NY