Dom Knigi, Leningrad, 1977 - at this time, I think the "official" exchange rate was such at a ruble cost something like $1.33. But the "unofficial" rate was probably 8 rubles for one dollar. (I don't remember more exactly; anyway, I had no reason to exchange dollars for rubles that way.)

<a href="http://www.vintagecalculators.com/html/the_pocket_calculator_race.html" rel="nofollow">www.vintagecalculators.com/html/the_pocket_calculator_rac...</a> says, describing the production and pricing of calculators (outside the Soviet bloc, naturally): "By the mid to late 1970s the calculator market had matured. Calculators had stopped being high-cost items for the few and were now low-cost commodity items for everyone."