Yes a company called Kimpex makes one. They make plows and other ATV accessories too. It costs about 2000.00 for the blower but then you need to get a 12 horse engine to power it. The unit is supported by its own wheels and is lifted with a winch or manually. If you cant find them on the internet I can get their phone number for you.
Polaris snowblower comes complete with engine. The one I seen, has the blower in front with the frame extending back underneath the ATV. The engine is mounted behind the machine. Quite a contraption if you ask me.
I bet it would be easy to buy a used blower, and adapt the parts to fit on a ATV. You could also buy the parts and the engine seperately.
A snowblower is a very simple machine, especially when you don't need the transmission. I mean you have the auger housing, the auger, the impeller, the discharge chute, and the drive pulley. All that when assembled, is attached to the other half of the snowblower by 4 bolts in most cases. All you'd need to do is make a plate to mount the engine on, and......
Man, sorry, I get carried away sometimes, I am supposed to be finishing my next snowplowing newsletter!