I bought a really nice warranty on the 4runner when we bought it, 100% of the factory warranty extended until 100k+, zero deductible. When I decided to lift it, I looked at the warranty and the verbiage was that the warranty was still in effect with modifications, just not for the parts associated with the modifications. Well, since it is full-time 4wd, I figured it fubars the entire warranty as it is all associated.
Called the company, sure enough since it is modified for off-highway use, everything but perhaps the seats are not covered. I cancelled it, and it cost me a little over $200 to have it when the truck was unmodified (I was refunded the difference).
I think it is best to just have a savings account with a couple of thousand in there for anything big...even though it is only earning you 2%...