I'm not a big fan of storing a car outside over the winter. My daily driver truck is parked outside all winter and it shows. My car cover says it protects the car from snow but I think that is for an occasional snow, not all winter long. If moisture gets trapped against the paint, the paint will get little blisters or pock marks. Between that and the wind damage from the cover that new paint job wont be nice very long.
If I were you I would sacrifice the garden equipment to outdoor storage and squeeze the Duster and snow blower in the garage. I don't care as much about the paint on my tractor as I do the paint on my car. If you do end up paying for indoor storage it definitely won't cost what a paint job does.