Very unscientific test but, a quick comparison of the Dayton blower in my paint booth with the exhaust fan in the bathroom and I'd say the Dayton is just a little quieter. I'm using a 265cfm Dayton and the number in the Grainger catalog is 4C447. I only had to run the ductwork a few feet to a window and with the size of my booth, this blower works great. It's true they don't sell retail but my boss let me buy one through work. Maybe you could do the same or possibly you have a friend in a position to help. I paid $62 or $63 for mine.
I've never seen one of the Aztec or MicroMark booths in person, only pics of them and am not familiar with the Artograph booths. MicroMark has some diagrams on their site but nothing that really gives away what type of fan they are using. After digging around and trying to decide what type of fan/blower to use and looking at a lot of different stuff, I'm wondering if they aren't using some type of bathroom exhaust fan on those booths. The thing that makes me wonder is the way the bottom of the booth is constructed. I found an exhaust fan at Home Depot that was rated at 300cfm, had two exhaust connections for 4" ducting and looked almost exactly like the bottom of these booths. It was twice the price of the Dayton I bought and I seriously doubt that it would be as durable.
Granted, the blower I got isn't *explosion proof*. The motor is not in the exhaust flow but fumes could still get in around it. If I had it to do over, I may have waited and spent the extra for an explosion proof blower. IIRC, they were about twice what I paid. The bath fan I found at HD was similar in that it used a squirrel cage fan with the motor out of the airstream. A lot of people use these types of fans/blowers and I've never seen anyone mention having a problem with fire/explosion but be aware, the risk is there.
With a little thought and planning I see no reason why you couldn't build a very nice booth at a substantial savings over any of the pre-fabbed booths I've found. Of course you have to consider your time and have the resources available to fabricate one. A friend helped with mine and that made it much easier. Sorry for the long winded reply but I know what a tough time I had making a decision on what to do. Hope this helps.
Here's a link to some info I found helpful: http://modelpaint.tripod.com/booth2.htm