I've only been collecting since 2001-02, when I stumbled across original art pages on eBay. I bought a Dazzler page w/the FF on it for something like $15. Even at that point, which is now 20 years ago, eBay had tons of great pages. I bought a couple of 80s covers, including a Micronauts New Voyages one, for under $300. I remember being gobsmacked to see Bob Larkin's cover to the Empire Strikes Back Marvel Super Special issue pop up on eBay w/a BIN of $3000, which seemed astronomical to me. I waited 15-20 minutes before deciding to pull the trigger; too late, it was gone. Never seen that one pop up again.
The comic art-l group is where I really started to learn about the hobby, and meeting other collectors. Probably the first conventions I attended to look for comic art were the Big Apple Cons held in the basement of St. Paul the Apostle church on 60th street, back when I was living in the city. just a few short blocks from my apt, I had the chance to see legends like Dave Cockrum in...2002, I think. I wish I had taken the time to talk with Gene Colan, Herb Trimpe, George Tuska and some of the other greats at that show.
It's funny that, even though I started collecting in the 21st century, I feel like the hobby has completely changed. I can't imagine how different it must feel for longtime collectors who have been at it for way longer.