I still have all my stuff from the 80's/90's, or most of it anyway.
I think I gave my cousin an old Rule Book of some stripe once I had newer ones.
And I think I also gave away my 6 BT Book/Page# games that were based on the "Lost Worlds" series of game books. (Locust-1S, Wasp-1A, Rifleman-3N, ShadowHawk-2H, Griffin-1N, & Warhammer-6R)
Other than those, or a few mini trades, I've kept most everything I've ever gotten, takes up several drawers in a large dresser.
I'd say the only thing I still think about getting that I search E-Bay for every few months is the last 7 mechs from TRO3025 that I have never owned.
I have 48/55 of them.
Firestarter, Urbanmech, BlackJack, Scorpion, Ostroc, Ostsol, & Goliath.
But I wouldn't throw handfuls of cash at them, the entire reason I never owned them was I rarely ever used them.
Its mostly just to say I completed 1 TRO of Minis, the original, and biggest IIRC at 55 Mechs.
The first 3 aren't too hard to find still but the last 4 in their original casts are very rare/expensive when I see them.
I sort of stopped adding much paperback into my collection a couple years ago, there is no more room, LOL.
At least not till I can retire in 20 years to somewhere that has basements to convert :) (AZ basements are rare)