I wouldn't get anything smaller than a 28" 10hp blower. Not sure if that'll go through your door though. If you shop around you may be able to get it for between $899 and $1k.
Many use the tried 'n true Tecumseh 10hp Snow King engine with electric start.
Another factor to plan for is wet snow, wether deep or not. My neighbor has a 5 hp Simplicty and it completly chokes in wet snow. Meanwhile I'm pumping it 15-20 feet with my Canadian made MTD.
...and don't forget iced over snow. My blowere doubles as a rototiller when it needs to.
