Buying privately

Hi all

I'm looking to buy a van conversion just for myself, but dealership prices go from £25k upwards to £45k+ which makes me blanche. I know that dealers have whopping markups as I sold my old Chausson Welcome to a local dealer for £14k last year and I know that they had it on the market for about £20k. Which is fair enough - they've a living to make and people to keep in work. I'd like to look at private offerings, though, and avoid dodgy sites like eBay and Gumtree, so:

a) can folk here suggest websites or fora where you can find private sellers?

b) what precautions/checks would folk recommend before buying privately?

I did have my Chausson for a few good years but it was an awful tank to drive and my partner was never really into motorhoming, so it was pointless keeping it. I'd like to take trips to the Highlands on my own in a vehicle that's driveable on single-track roads, hence the desire for a van conversion, but I don't want it to cost an arm and a leg and an internal organ.

Cheers

Fred