They look a little expensive for what they are; I also only need a compressor.
As a quick review, you can get an Iwata HP-CS and a Iwata compressor with a tank for about the same price; Iwata produce very good airbrushes and is a very well known name. I personally do not like the pistol action brushes, though some people do; the Grex pistol grip is a single action, which means it does not let you control the amount of air and paint at the same time. Only the two most expensive units have different nozzle sizes available; and I am not sure how easy they are to get, or how much they cost.
It looks like a great starter Air Brush kit, though a little expensive. I would feel fine recommending this as a nice starter kit for someone just starting, and are going to use it mainly for modeling. The kits also includes a Getting Started DVD. The Grex unit will look very nice if you were to get one and have it in stock to sell; and I don't think many other brands would look as like. I don't think you will sell many to someone that already has an airbrush.