HO train enthusiasts?

Best bet is follow ebay.

While I agree most wood kits are not exceptionally valuable, if they are built to a high degree, they can be $50-$100 or more. If the passenger car kits are for specific plans they could be valuable. generic kits, probably not.

Agree it depends on brands and condition.

If the turntable is a Bowser, they have taken an upturn in pricing.
I bought a few when they were $25. Now I see them $100-$200 depending on size.

I disagree about the hobby falling apart. In fact right now is quite possibly the golden age of MRR.

There are some newer model companies (Rapido, not the old N scale Rapido, Exact Rail, and Scale Trains come to mind) that offer extremely well detailed models, albeit at premium prices.

Scale locomotives are now sound enabled, have onboard network cards, and can come from the factory with details specific to the actual engine number.
Prototype signaling is becoming more embraced, along with the associated complex logic and detection.

Most of this means older, non-tech capable, non super detailed models are not in high demand.

Pics might help.