I haven't gone to these things with an eye on the ebay potential. Maybe I should, and Morse keys, a thing I've taken no interest in whatsoever, would repay some attention.
It does occur that anything small and neat, such as little audio oscillators, or those plastic cased RF sig gens rebadged as TenMa, Rapid etc, fetch an obscene amount on fleabay. If they don't work, they usually don't take much to get them working and it's fun. You can calibrate them to within their spec if you have halfway reasonable test gear. Clean them up, and a nice photo... I'd rather sell working stuff.
Then there are valves. There must be all sorts of things.
Transistors. Imagine hitting paydirt with a bag of 100 fabulous TI BC183Ls for a couple of quid.
Yes, I must get in touch with my inner Ferengi and see rallies in that light.
I'm beginning to feel I must have left RATS with treasure unlifted.