BC is the most expensive province of Canada. It is very beautiful and has mild winters compared with other provinces, hence its attraction.
We rent a 2 bedroom (just over 1000 sq ft) basement suite about 50km east of Vancouver. This costs $1050 per month, but that includes all bills (electricity, water, internet etc).
For family of 4 you'll probably want a least a 3 bedroom apartment, so I'd say you're probably looking at $1200 per month or so if you live in the suburbs such as Langley, Walnut Grove, Surrey etc. Gets a bit cheaper if you go a bit further away from Vancouver - Aldergrove, Abbotsford, Chilliwack etc. And of course more expensive the closer to Central Vancouver you get.
Probably the biggest "sting" about BC is the car insurance. Because ICBC have the monopoly on the minimum insurance that you have to get, they can (and do!) charge what they like. Our car insurance is about $1700 per year (but that's with only 1 year no claims at 5% it goes up to a maximum of 8 years at 40%).
Wayne.