Provided they're in really good shape, not scratched up and not sun baked, I'd add up the average price of new for the major components Bare panels, $275, Window and door switches $160ish, Arm rests $60, Misc $50 divide by 2 = $275
About half price is more than fair IMO.
Then depends. Guy rolls up in a new Duramax and shows you pics of his $30k build, and actually wants your OEM door panels add $100. Guy drives the truck he's needing the panels for and has to use the outside door handle to get out of the truck, sell em for less.
Generally if I'm selling used parts, I try to be super fair. I'm not in the parts business and I hope others will be fair to me.
Just saved a guy buying $500 worth of new brackets for his boat swim deck (have to buy the whole set, 4 pieces) because he needed one of the pieces. I have a complete spare set of brackets. They're about 50x more rare than square body door panels fwiw.
Told him free or a 6 pack. He brought me a bottle of good small batch bourbon. I'm good with that...
Tires are another good one. People with 90%+ tread set of desirable tires sometimes try to get 80-90% of the retail cost. Buddy I'm sorry you paid $130 in sales tax and they charged you $30 a tire to mount them and $20 a pop to remove 'em on top of retail rate with your new Rockstar wheels. Top $ used is the cost of 3 of the same tires online.
And btw 50% tread does not equal 50% of the original cost! Used to be you could get good deals on used stuff. Now thanks to the internet and TV shows like Pawn Stars, Storage Wars and Fast n Loud, everybody thinks they're Richard Fckin Rawlins!