I had a 2 post symmetric floor cable lift at the old shop - I never thought it was a big deal having the stuff on the floor, and most of the cars that went on the lift were pushers. I found it on Craigslist, paid $1500 for a nearly new 9K# Bend-Pak from a small shop that was downsizing. Probably going to be more of that going on.
Do you know for sure that your slab is thick enough? FWIW, here's a install/operation manual from Bend-Pak:
http://www.bendpak.com/files/215_1491777197.pdf