I swear by the Turbo Maxxair fan. It's outside so you don't hear it. I have the vent to it open since I bought it. If you have 2 vents, close all the windows and turn that Turbo fan on exhaust you can create a tornado inside your RV!
That said I looked for the website to copy a picture of one for a fan thread and it looks to me it may have been bought out by another company for distribution but you still can order them.
YES you can still get them just not direct from them anymore.
Ask your local camping store to order one for you. They have the catalog number and supplier info.
Friend of mine just got one last week from their local camping store. And/or go to your local camping stores that are within local RV dealerships.
Item model number 00-965001
Manufacturer Part Number 965001
IMHO I think MaxxAir wanted to get out of Amazon selling them. That's why on the Amazon site it says discontinued out of stock to them. You can order them thru the camping stores though.
http://www.amazon.com/Maxxair-00-965001-Turbo-Speed-Thermostat/dp/B0002F67K0