For finding a shop, you might want to post in a forum that isn't platform specific- perhaps something like the General forum- you will get more visibility there, so chances of getting someone in the area who knows of a good shop is increased.
For what you want to do to your suspension, that is pretty much what I've done. It is super inexpensive, and that is the main reason I went with it to start out. I wanted to see how I was really going to use my GX and what I wanted long term before I dropped a bunch into suspension. It isn't bad, but you definitely get what you pay for. I don't feel that the Bilsteins up front are as nice as the stock suspension (ride wise), but they aren't horrible. They make the GX feel more like a truck than a luxury SUV. Tricking the airbags definitely make the rear a bit harsh, even with a heavy steel rear bumper. I wanted to keep the airbags since I pull a trailer, but when it tops out, it does so with a bit of force and causes a bit of a bump.
It isn't bad for now, but I'll definitely be upgrading my suspension sooner rather than later. Post #115 in the 120 series photos thread is my GX if you want to see what mine looks like with this set-up.
Also, if you are looking for a shop mostly for installation of the lift, you might look into doing it yourself as it is super simple to do. If you have a good set of hand tools, floor jack, and jack stands (and a place to do it), I would really think about doing it yourself. There are good how-to
videos on Youtube; it took me about 4 hours to do both the front and rear lift on mine following a similar method to the video I linked.
