We're not MH-ers (yet?), but some thoughts...
RV-ing is fun, fun, fun! You can't buy any other kind of fun for the kind of money you'll spend. The places you'll go, the people you'll meet, the things you'll see and do, the things you'll discover, the feeling of getting away from it all.... Priceless.
Good to be thinking about purchasing a newer previously owned MH. The bigger chunk of depreciation will be at the beginning. At least by talking about it here, you know you're going to take a big hit in advance if/when you do go to sell it and don't end up with a heart attack.
You could be thinking about something with worse depreciation like a boat. Around here (west coast of BC), you can't give them away. I know the economy in the US isn't that great, but would a $50K loss be the end of the world for you? Is that $50K of future inheritance that your kids something could really use and are you going to have feelings of guilt after? But, you aren't getting younger and things can unexpectedly change at a moments notice. If you haven't ever done something fun just for yourselves, indulge and just do it. We indulged and bought a TT 2 years ago in advance of DW retiring with the thinking that health could change overnight at any time and we would rather enjoy travelling and RV-ing now while we are both healthy (DW's mom died from cancer in her fifties and it's always in the back of DW's mind).
Why would you only keep the MH for a few years after your kids graduate? Not sure of your ages, but the majority of MH owners we see in cgs are in the 65+ year old range. Maybe keep it a lot longer than you are thinking of right now? We have a TT, and have had some say we WILL end up with a MH down the road. Can't see it right now, but who knows, I used to say we'd never own any kind of RV.
Is this the first RV you've ever owned? Why not buy a used one for a lot less or rent one for a while? A lot of times, RV owners end up upgrading to something bigger and better in a short period of time. Maybe you'll be at an RV show and see something you just hafta have. Then you've got to unload the MH you just spent $100K on. We upgraded our TT just one year after the first one we bought after we saw a bigger and better one at an RV show that we fell in love with. Happens all the time.
Depreciation may be a huge cost, but what about maintenance costs in a MH? I read all the time about major things that break down and cost a bundle to fix. Checked the price of a new set of tires? They ain't cheap on a MH. Is Tiffin one of the better makes? I don't know anything about MHs, but I do know from reading that some are bad news and bad quality and costly to fix all the things that go wrong. And sometimes when things do go wrong, you can't always just drop into the nearest RV dealer. Sometimes you have to go to the plant. For the non do-it-yourselfer, things on MHs can be more complex. The repair and maintenance costs that I read about on MHs scares the dickens out of me. A MH just seems to be like Texas - everything to do with it is bigger.
Have you got a big lot to park your rig on or would you have to rent space in a storage lot that would yet be another expense?
Are you going to buy a toad for your MH? That's another big chunk of dough too (not to mention depreciation, etc.).
What would you do if you didn't buy the MH? Stay at home and watch TV? Or would you be going on vacations somewhere? If you were to do a bit of travelling around the country or some trips out of the country, you could be spending $10K plus a year or so. At least with a MH, you could take your kids, grandkids and pets with you for little extra cost.
It's not just the depreciation of a MH, even at a huge depreciated value, when you do go to sell, it can be REALLY hard to find a buyer and it can take f-o-r-e-v-e-r..... I've seen MHs around here in front yards with for sale signs on them for 2-3 years.
If you really want to do some RV-ing, why not get a nice truck and trailer? However... A truck and trailer (5th or TT) can cost you $100K anyway. Not sure what my point is exactly, but maybe at least you'd have the use of the truck at home for other stuff (or for your kids)? Maybe the depreciation would be less?
If you want an RV that doesn't depreciate much, consider getting a tent trailer. For some reason, they seem to maintain their value better. (And for some reason, they're expensive to buy for what they are.)
It's too bad they don't lease RVs like with cars. I wonder why?