A 2 post is definitely NOT $40K in foundation work. It only actually needs (2) 4'x4' pads 6" thick (Which anyone could do in an afternoon for a couple hundred dollars). OK, you've got a 3' frost line. If that concerns you, then you have to make the pads 3' thick (which is still easy- just takes more concrete)- that would take 2 hrs digging with a backhoe, and 4 yds of concrete- about $500.
A slab could be added later (since you only care about oil changes, you could put crusher run down with no slab).
A 4 post can be put on wheels- sometimes useful (but still has a big footprint).
Have you considered a pit? A concrete pit could be built for much less than a lift.
