Boy, you either have a lot of money to throw down the drain, or you really have no clue.
Spending that much as a first timer on a deprecating asset is a huge mistake. If you were to spend 350K today to buy that luxury motor home and six months or a year from now wake up and discover you really hate the life style. What now? You basically try to sell it and discover that it is now worth maybe 200K. Even less if you drop it at some dealer on consignment. Maybe you should rent a MH for a few weeks first. Heck at those prices your apparently looking at a diesel pusher. Having that much disposable income I have to assume your prepared to spend thousands a year on maintenance?
