Tirerack has TPMS sensors for the new '17 CX-5 for $49 ea. They claim they are real OEM sensors.
I've been debating getting a set of winter tires/wheels even though I'm in Portland Oregon. We've had at least one good dump two of the past three winters, and last year we got around 16" in one storm. Doesn't sound so bad, but Portland doesn't have any plows (because it doesn't snow much) so the snow sticks around until it melts. Last year that meant about two weeks of difficult to impossible driving. Especially if you live in a hilly area, it can be really tough to get around. We got through it last year with an AWD CRV on all-season Michelins, but there were a few close calls.
For a little over $1K, it might just make sense (especially since we go skiing a lot).
Good for at least 5 years of use. You will be surprised how well they work in the cold rain too.