Model railroads.
I have some oddball equipment I bought from the factory yard sale at Broadway Limited.
Pre-production prototype NYC 4-8-2 and PRR GG1.
"Lawsuit" prototype PRR Alco FA ABA set (all with LokSound)-(tooling was surrendered to MTH).
I had and sold a prototype N&W J1.
...and I bought a bucket full of 21pin ESU Loksound decoders.
The FA's, and a 99% complete K-4 4-6-2 were the most expensive at $40 each.
Everything else was $25 including another 85% complete K4, a couple of I1 2-10-0's and a half a dozen tenders with Quantum decoders.