I bought a 60", PTO driven blower(The Blue Machine) the year after God invented snow - 1982. The company is no longer in business. It worked well - was chain driven and only choked up on wooden fence posts and large rocks. If you live in snow country - have a driveway to maintain - then buy a blower like you really mean it. Neighbor always gave me gassss because I spent about $450 more for mine than his. Boy - did he EAT CROW the morning he came over and asked if I would blow his driveway. His POS had completely fallen apart.
I kept and used the blower until 2009 when I got the Kubota M6040 and it was heavy enough to clear the driveway berms with the rear blade.
The key to keeping a blower working - keep the gear box full of lube and keep the drive chain well oiled. I always stored mine in the carport and out of the weather.
BTW - your math is correct. I kept and used the same blower for 27 years. No repair parts needed - nothing ever broke - got exactly what I originally paid for it on trade in.