Vancouver BC, eh? You must be getting walloped by the same wind we are! But we haven't lost power, amazingly.
Xantrex PowerSource 400. I've got one and it's great.
You can get them at Best Buy for around $150. Watch your sale flyers... sometimes they have pretty good deals on them.
It's hard to tell exactly how long it would keep a 50W heater and small HOB
running. The HOB
is probably no more than 10W constant, and the 50W heater is probably running maybe 30% of the time? My guess is you'd get 6-8 hours or so out of this unit.