I bought a 2 post hoist on eBay for only $620 bu it was 3 phase ... I just spent $540 on a 5 HP singlphase motor to replace the 4HP 3 phase motor - now just have to get a sparky out to wire it up.

Having said all that you basically have 2 options for the hoist. Either screw post (like mine) where you have a worm drive screw in each side connected by a chain so that the motor on one side drives both screws or a hydraulic lift where the motor drives a pump to lift the car.

the screw post must work both to lift and lower while the hydraulic only lifts and a relief valve controls the lowering.

i believe that the screw post is safer since the only way to lower the car is to run the motor backwards via a switch (i.e. the car can't fall unless both the lift nuts and the safety nuts are stripped - extremely unlikely). The hydraulic hoist will usually have a locking mechanism where you lower the car down slightly to lock it.

You should also consider wheter you want to go clear floor (hump or no hump) Hump means that the chain (or hydraulics) run on the floor clear floor will mean you have a horizontal connection over head.

Keep an eye out on Gray's online and ebay but be careful of the cheap chinese stuff on the market.

Good Luck