Being a southern boy I'm going to ask a stupid question about northern roads. Are they really so bad that you couldn't just rent a drive on car hauler from Uhaul and pull it to your house?
Honestly, it depends on the day. If it's dry, hasn't snowed in a few days, and is cold enough that there isn't any slush, the roads would be good enough that I could probably drive the car home safely. The problem is the salt. Like HotFox said, it gets everywhere. When it's wet outside, it dissolves in the melting snow so when you drive through it, it sprays onto the car and dries into a nice caked-on mess. When it's dry out, it gets ground up by the tires and thrown into the wheel wells. I don't know if an open car hauler would be enough to protect it from salt thrown up from underneath.
Also, the seller told me that the last time he tried to get it onto his trailer, it tore the exhaust off the bottom of the car, so a uhaul may not work.
I would let him store it or find a buddy with a enclosed trailer. If you do get impatient try to move it after a rain when the road is dry and or do a good rinse after it is home especially the underside.
I do have a former boss and family acquaintance that has a low-profile enclosed trailer that he uses to haul around his show cars. The problem is that it's a big beast. I think it's a two car trailer, so it's probably a pain to handle even when the roads are clear. I'll ask him about it.