You're quite right.
Maybe you could get a cheap piece of shit lift for 5g's, but a whole garage?
The excavation alone must be 5 g's...not to mention the electrical (600?), structure/thing that has to support the weight of 4 cars and a STONE DRIVEWAY (must be 10 k min), the lifts (15k), and then the labour and specialization required to do something like that...
I think K-rob is missing some zero's from his guesstimate.
If it was 5k, it would be MUCH more popular.