The Revolution lift seems to be the lift that most Viper owners use. There was a group buy on them about a month ago. I am still debating whether or not to get one. The local dealer wants $4000 installed, so it is quite a hefty investment. Do you need more parking space or just want to work on your car? I, myself, have plenty of garage space so I don't really need extra parking. From what I can see that is probably one of the few advantages a 4-post lift has over a 2-post lift. A 2-post lift is probably a little easier to work on the car as well as offers unrestricted access to the wheels. 4-post lifts need jacks to to have access to the wheels. However, one problem with 2-post lifts is that they are not as fool-proof as the 4-post lifts. With 4-post lifts you just drive your car onto the lift, whereas with 2-post lifts you have to determine the proper jacking points of the car. If you screw this up then you will be screwed.
Fred Driving School Kinder currently has a group buy on the Bend Pak lifts. They are about the same price and quality as the Revolution.
If those lifts are too much, Ab also had a group buy on a 4-post lift. It was about $1400 cheaper than the Revolution. I believe you can get it for $1850 plus shipping.