Don't forget you need to overfill a raised bed at first, to compensate for settling. What you buy will be all fluffed up when you first put it in, and may settle 3 or 4in. in the first couple of months. Better to start with more depth than to end up with too shallow soil in the bed.
If you're in the Vancouver area, check with your local landfill. Some of them were making compost the last time I was there for a visit. (I used to live in W. Van). Fraser Valley area should have farms with composted manure for sale, too. Even Richmond and Surrey areas still have some agriculture going on, where there may be good soil available.
