If you get a turbine setup, don't get anything less than a 4 stage, like Stagmitis has. Since they use a vacuum cleaner motor, they need to build pressure in series. And since it is pretty much just a vac motor in a metal housing, it's very simple to replicate and improve. I used a homemade unit for years. It was one 4 stage motor in a 3/8" plywood box. Heat is the big problem with turbines, if you are running them for any length of time. A homemade box lets you increase the filtered intake are by 400% or more, plus you can mount a muffin fan to move air out of the box. If you are going to be spraying more than a couple quarts of material, you can run a pressure pot setup from a bottom feeder gun. A set up like that could be put together for a few hundred and be quality.
For the $1000. or more spent on a plug and play turbine unit, I think I would get an 80gal compressor and a really "Bitchin'" gun