I believe lesser collectibles are easily sold. The problems is, you cannot rely on prices always going up or even staying level.
Lots of personal value of firearms disappeared overnight when some governments banned them. A classic case is India, where double rifles worth thousands of dollars became almost worthless with a ban on hunting and extreme difficulty in selling and transferring rifles legally.
India even made the export to the rifles illegal, because they were "cultural artifacts".
When I said "sold," I should have clarified that to include "at an expected price."
As you say, just about anything can be sold at a fire sale...even a Van Gogh.
California seems to be doing the same.
Formally legally owned Then outlawed with no way to transfer. Destroy, turn in to LE or Move to a Free State are the options for protecting your property.
I choose the later.