In general, there is a glut of standard components around as we all upgrade. As we’ve not paid an individual price for these parts, they were included with the van, the resale value is
arbitrary - too high you’ll sit on them for ages, too low and they’ll be snapped up.
An example I sold a folding double front seat for £120 but a bulky item was gone quickly.
I’m not looking for anything hence not trying to reduce prices, just being realistic. A quick look on ebay will give you guide prices.