A single stage unit with a two stroke engine sounds like what you should have. They work great in snow up to 6" or so, more snow is expected you may need to go out more than once. If that's an issue than you may need to go for a bigger two stage unit. As far as price goes, you get what you pay for.....

I wouldn't recommend leaving it outside. Isn't there room in the garage? Even in an unheated garage, it'll be a few degrees warmer and a lot dryer. The warmer and dryer it is, the better it'll start.

A single stage two stroke would work ok but I'd be concerned about throwing the snow the width of two cars with a single stage blower(with wind as a factor, you might have to throw it the entire width of the driveway). They're more for a two car driveway less than 50 feet long and sidewalks. Mixing gas and oil is a hassle as well. Personally, I'd go two stage, 5HP+, 20"+ path. Anything over 8HP and 24" is overkill. From what I've seen in Madison WI craigslist, you should be able to get a blower with these requirements in your price range no problem.

Like two stroke said, you get what you pay for. The more mechanically inclined you are, the more risk you can take. I just got a simplicity 2.7HP, 20", 2 stage, electric start for 60 bucks off craiglist. The small engine is a concern for me but the price was right. I did have to fabricate some tire chains because the solid rubber tires were worn smooth but that wasn't a big deal for me. If you have limited mechanical skills, you should pay more for a better machine.

Sorry, I can't give you any advice on makes and models. I don't know much about any specific ones.