Besides the popularizing influence of shows like Breaking Bad, I think that it's quite likely that gun and RV sales are linked. Both are something that would be purchased by a prepper, since they offer protection and mobility. I wish that I could get an RV, personally. Not that I'm a prepper.
That is interesting that RV sales seem to have increased as the economy has gotten a little better. My brother has been talking about buying an RV, although I don't know if he has bought one yet. It seems like with RVs being a recreational expense, that it would probably depend on the person and their preferences as to which one they decide to get. http://www.rvnorthwest.com