I've done it from time to time. Some things off the top of my head.
Snatched up at a comic book store clearance sale an opened box of Meanie Baby cards and Hildebrandt cards. I also picked up a complete set of Wizard of Oz cards. (I also snatched up a set of four oversized never used MTG promotional poster cards, but that's not nostalgia. Still trying to figure out how to sleeve them).
Purchased a few bits and bobs from eBay related to Lunar (a boxing toy and a medallion). Also found some Atari related hardware such as the SIO cables and a SIO <-> RS232 adapter port box. Just recently picked up two vinyl records, one is
Super Breakout and the other is Missile Command. About two years ago, an
AtariAge fan digitize his entire collection and put it on DVD. Unfortunately, I missed out on that deal. Hopefully, they'll upload the DVD soon. I did find a website that did have some of the MP3's, but I can't figure out where it is now. (just discovered GameArchive is gone. It's been two years?)
I went through an old book phase for a while. Picked up books like Little Fuzzy, Barnstormer in Oz and 20,000 Leagues Under the Sea.
There's a few others, I just can't think of them right now.