I am happy to help out! I don't feel like you're bugging me at all :-)
I ended up paying $99 for the one above. I honestly couldn't find a huge difference between most of them. They all seemed to be a compressor unit with some type of airbrush gun.
The unit I linked to is a kit, and comes with sample bottles of about 4 different shades, plus the primer and pearl shimmer. Either in matte or glossy. Even those samples will last a month or so each.
Airbrush makeup can also be mixed to get just the right shade. Just put a drop or two of the colors you want, and mix. (I sometimes use a toothpick to mix it in the gun's reservoir).
Also airbrush makeup works differently than liquid foundation. With airbrush makeup you get the super fine mist, and are able to control the strength and flow (fast vs slow) of the mist. Airbrush makeup unlike regular liquid foundation gets built up over the course of several passes on the skin. This helps with that flawless makeup look, as you can cover any flaws with a couple extra passes, and simply by moving the gun closer or further away from the face can "blend" the areas with flaws into everything else.
The other advantage to the build up technique that airbrush makeup uses is that you have a ton more flexibility with the colors you choose for the foundation. If you have pale skin you can go with a color that is much darker than you could get away with if you were instead using the classic liquid foundation. Reason for this is your skin color still influences the color even after makeup application. I.e. Because the makeup is applied so thinly you can balance out any darker shades with lighter skin. (Where's liquid foundation has more of a tendency to simply cover up the color of your skin, and then your stuck with trying to blend it into the edges where you're not using it and it's super obvious when it's not a perfect match. (Same thing when the face is completely covered with a typical liquid foundation, the face itself might look great, but it doesn't match the skin color on the rest of your body.)
Hope this helps, any more questions let me know!
~Brooke~