A mechanic I very occasionally speak to in B'ham used to sell them(diesel) for £100. He got them from old buses. I bought one from him about 8 years ago. They are very good. If u want a gas one you used to be able to buy ex BT van ones for £25. I think I have one in my garage that I never got round to using in my caravan.
the gas ( made by propex ) are now alot more money, after everyman and his dog started to convert vans to campervans
i have a Webasto heater, its still in the box from germany
i allmost had a deal with a Ebspacher dealer in germany, but i think he found out how much they were worth in the UK and got in contact with a dealer in the uk, the deal fell though
A webasto will now go for about 150 quid with the eber slightly more