Had a quick trip to Newton Abbot Toy and Train Fair last Sunday, they have one every two months or so and there are lots of Sellers/Dealers there, mostly trains and railway stuff.
I tend to go around first to see what is on offer and check the prices before deciding if there is anything I want and who is offering it at the best price. Prices can vary quite a bit fron one dealer to another, but you can always make an offer and see how much they want to sell.
I did that on Sunday and got four coal wagons, three with good loads, for £10, they were on offer at £3 each with is about the best price you can get for second hand trucks. Just had to check that they had all the bits and that the wheels run freely, and then find the cash. I also saw a singe matching truck in a box for £2.99 so I had that as well and a Diesel Shunter for £12 which runs, but I will have to convert it to DCC first for my Layout.
I still have to construct the Terraced corner shop I bought at the last fair, so I have been quite please with my last two visits.