I justified my snow blower in the same way I justified my riding lawn mower: how much time is it saving me, and what is my time worth?
For my large driveway (about 50' X 40', or 2000 square feet) it takes minimum of an hour to shovel an inch of snow by hand. I can use the snowblower and have it done in less than 15 minutes. As the snow gets deeper, the time savings becomes greater. At a foot of snow I'm looking at 3+ hours of shoveling by hand, or 1/2 an hour with the blower. We probably average about 10 snows a year that require shoveling. At the end of a season that adds up to a significant number of hours saved, and those are hours I'm not spending out in bone-chilling cold.
My now 10 year old snowblower hasn't required much maintenance at all to keep it going. Oil change once a year. A new spark plug every couple years. Occasionally replacing a shear pin or skids. Much less than an hour's worth of work per year.
Similarly, my 1/2 acre lawn was taking me 2 hours to mow with a push mower, and I was having to mow about every 5-7 days or about 30 times per year. My riding mower takes 1/2 an hour. I figured out that over the course of a single year I would save 45 hours of work, and that was work I didn't particularly enjoy doing. I'd rather spend the evening mowing for 1/2 and hour and then playing ball with my son, vs spending the whole evening mowing. Once I looked at it from that angle it was a no-brainer to buy a riding mower. Maintaining my riding mower doesn't take much more time than maintaining my push mower.
Of course some would argue that I could save the expense of both machines by moving somewhere with a smaller driveway and lawn. Perhaps, but my house is paid for and I like it here, so I accepted this as a reasonable concession.