No Kevin they tend to hold their value far better than the average car. You have not said where you live but the local Peugeot dealer in Bridgend "Tondu Road Motors" has started selling motorhomes and at present has 10 in stock at very reasonable prices and offering on most of them 12 months warranties. The chap who owns the business has owned a motor home for many years os is knowledgeable on them. Also try Barry Caravan Centre as they have quite a few in stock at reasonable prices. "www.barrycaravancentre.co.uk" and follow the link to Castle Motorhomes.
Also have a look at the sister web site to this at Practical Motorhomes - very slow site mind. I think at present it is gas fired.
What Colin says is correct, so long as you sell your motorhome privately. In other words, don't expect a lot back if you are trading it in, to a dealer. I have heard quite a few horror stories about that particular scenario. A case of seller beware.