Do you mean a proper mobile single post lift or one of the push under types discussed below?
I have one of the push under types, made by OECM - another one of those Italian companies that make all sorts of garage equipment.
If this is the type you mean then here are a few pointers:
1. You need a very flat and level floor. 2. Largest vehicle I've had on mine was a Grand Voyager. 3. The steering handle is too short to push under many vehicles to load easily. Sometimes the handle needs removing and the vehicles pushing forward. A minor irritation. 4. Make sure you get one with screw type rubber adjusters for the jacking points. I've seen them with a set of metal blocks, and these are not as versatile. 5. Mine was £700, second-hand. New around £1500. 6. You will struggle with low vehicles, but this can be overcome with a couple of trolly jacks to lift the front of the vehicle slightly. 7. Ideally you want to be in a situation where you push the ramp under, rather than drive onto it.