Funny, just today during spring cleaning I came across my collection and looked one up online on a whim (Topps '92 Derek Jeter Prospect card). $0.99. Good thing I saved that thing in a soft plastic AND hard plastic sleeve! One version was about $215, but that was in some nuclear safe plastic-case with screws and valued by one of the numerous memorabilia agencies.
The poster that mentioned the sub-sets is right, but to me only half-right. The '94 strike killed it as well. Also, adults killed it. I recall there were at least half a dozen card shops in my town in the time of my collecting days (mid 80's to mid 90's). I took a few fantastic trips in my formative years to Florida for some Grapefruit League action with my father. We even stayed at the same hotel the Cincinnati Reds did that first year in Plant City, FL. Lou Pinella and Barry Larkin signed some cards and gave me sage advice about women around the pool.
Anyway, to my point. I got back into town and went to some card shops to see if any of my cards had increased in value. If I could sell a signed Larkin to get 20 more Will Clark's to add to my favorite player collection, I was all for it. Most of the proprietors resembled the
Comic Book Guy from the Simpsons. Several of them told me they wouldn't dare let Nolan Ryan sully one of his own cards with a Sharpie for fear of ruining the mint condition of the card.
To recap on my long 300th post. Over-saturation, Douchebag adults in a kids' world (with whom I had to compete for an autograph in places like Lakeland, Tampa, Orlando, St. Pete), and the '94 strike killed baseball cards, the joy, and their subsequent value to this day.