WARNING -- Blather and Trivia Follows!
Yes, the penny would have been a good deal, even with inflation.
Just for a lark, I just checked how the current 28-cent rate compares with previous rates in constant dollars. The turn-over point was in the mid-1960's. Inflation since 1964 averaged 4.32%, so the 4-cent postcard stamp then corresponds exactly to the 28 cents a postcard stamp costs now. But by 1974 the postcard rate had doubled to 8 cents, which corresponds to 37 cents in 2010 (average inflation of 4.38% between 1974 and 2010), making today's 28 cents look like a bargain. So chess by mail cost the same as now in 1964, but was more expensive than now in 1974.
Postcard stamps cost 1 cent from 1898 until January 1, 1952. At the end of that span it was a bargain-- 1 cent in 1951 converts to 9 cents today. Obviously, the farther back you go, the less of a deal it was-- 1 cent in 1914 converts to 22 cents today (average inflation of 3.25% since 1914).
So the cheapest period for chess by mail would have been the years just before 1952, when the postcard postage would have had an inflation adjusted cost of about 1/3 the current prices.
--Cystem
EDIT: Just to be clear, these are U.S. rates for domestic postage.
I once had like 600...(greeter games)