I almost always negotiate on purchases at train shows and of course garage sales.
My MO is to buy used, or distressed trains, accessories or what ever. I have only bought one new engine and maybe a couple of new cars in 40 years. I love to hit the junk boxes usually under the tables or on the floor. I have bought engines missing wheels, wheel gears, missing a corner of the cab etc. Things I can fix or patch up.
I am not into new and shinny, in boxes, or latest as I like post war O gauge. I get most at a low fair price for the condition and will usually ask for a price lower than marked. Like many others, I do not have to have any train or train item. There is always another train show or deal on eBay or one I can maybe build.
Charlie