I got the shelterlogic garage. Its got about 10" of snow covering it now and no issues. Bought it last year, and it held up through a very toguh winter. Ordered it thu Northern tool..or Northern freight, for about 250, after searchin for an online coupon. Very good buy for my Challenger.
Don't have any experience with this, but I'm watching discovery channel and notice they are building a custom chopper for this company - but these appear to be more permanent structures then a canvas garage: