34 years of stamp collecting for this?

My Mum recently sent me my old stamp collection, which judging from the number of stamps from 1974, I must have been really into when I was 6 -- which seems like too young to be so incredibly boring, but such is my life, I guess. Anyway, I decided to look up some prices, and I had a fond memory of a fully mint collection of stamps that had something to do with Skylab. Sure enough, I found it! A folder of mint commemorative stamps from 1974 ... 29 unused 10-cent stamps, a $2.90 value in 1974. I typed it into Google with glee -- certainly, my 6-year-old self was about to "pay it forward" to my present-day self in a big way! Turns out, that set today is worth up to $9.95! Of course, $9.95 today, in 1974 dollars, is ... $2.90. So, the moral of the story is, I was about as good of an investor at 6 as I am today. I've got a ton more stamps that I could look up -- who knows, there is probably one of them worth something; unfortunately, most online stamp-price lookup services want to charge $20 a month ... and I'll just bet that I don't have $20 worth of stamps.