I need some cash for a big purchase item(car related)

I've been a ford freak for nearly 20yrs and have hoarded bits and pieces over the yrs. I've 6 fords nothing amazing, but I've collected and stashed tat away over the yrs; just odds and sods.

It's time to start downsizing and free up money but how do I keep on the correct side of the for sale rules and not be viewed as a trader as potentially it could be mistaken that I am when I'm selling many many items?

Many thanks