Besides all who bring up that you should think about how you plan to travel there are other issues to think about.
If you have all the money in the world and can afford a top end MH for $$$$ go for it. A 5th wheel and new dully diesel tow vehicle can also go big bucks. Now if you are not going to buy new other issues come up.
We have been full timing for many years in our 09 NuWa 38 ft Discover America 5th wheel and thought about moving to a diesel pusher motorhome. Why, because OK so I am vain and wanted to travel with like the big boys.
So we start to go looking on the internet for units to buy. Well, we are not made of money but not poor either so we're looking at mid-2000 units. Like 2006 or so. The price range was not too bad and after much research found several issues with older MHs. Like trailing arms that need to be replaced and steering box movement problems. All seems things that should have been fixed by the previous owners. THEN the big issue came up...
Full Body Paint Checking. You ask what is that. I did a search and found...
The thin plywood that is covered with the fiberglass and then paint is off-gassing an acid that is bleeding out to the surface. It is caused by heat and shows up in the dark colors first.
So the bottom line is buyer beware if you are looking buying a full paint older MH. Look at it closely for paint problems. This may not show up for years so buy at your own risk. I am not saying don't buy but be aware of all the issues. Just google "paint checking" for more info.
The above thoughts were orig. posted on rv.net in the MH section.
Now, 5th wheels also have problems to think about. Most are fiberglass gel coat and add-on decals. Yep the decals will degrade and crack and curl over the years. And without waxing often oxidation will occur.
So both MHs and 5th wheels have issues that will show up over time.
In our case, we have found it much easier to deal with oxidation and decal problems than paint checking issues.
So have decided to replace our decals (got all new ones from the factory) on our 5th wheel and put in a residential refrigerator Samsung RF18.
As most people will tell you don't buy NEW, it will be in the shop more than you get to use it.
And when on the road and you call up any dealer for service they will tell you ya bring it in in 90 days. That's works well when you are full-timing.
Hope you find an RV that suits your needs and love it.