I bought the Beckett app a few months ago to check a bunch of cards I had from the early 90s, I didn't like the interface then it auto renewed the subscription the next month and it was kind of a pain to turn auto renew off. I'm sure those that keep up with it more than once every 25 years probably know of a better way to check the value. BTW my Roger Clemens rookie card that's been in a case since I got it was the highest valued card at $15. I've got a Nolan Ryan 3000 strikeout card somewhere but I'm probably not retiring on that.
Like it was mentioned, overproduction of cards plus the ability to find cards online instead of having to go to your local card shop has really hurt their value.