You are right, well, I guess I like the Iawata the best, but the Grex is also very good.
That spray booth looks fine, although it maybe a little small in terms of working space. Mine is similar to this one http://www.amazon.com/Artograph-225-315-1520-Spray-Booth/dp/B000KNHTTC/ref=sr_1_9?ie=UTF8&qid=1415561561&sr=8-9&keywords=Spray+booth
It's similar in dimensions to yours just smaller on the height