I went to the VanDusen Gardens Plant Sale a couple of weeks ago and had a great time. If you're not exactly sure about what you're doing — and how many of us are? — it's helpful to have Master Gardeners on hand to give advice. The prices at these sales are as cheap as they get and the plants are very well cared for.
If you are looking for classes or local resources visit: http://vancouvercommunities.com/outdoor/year-round-activities/gardening.
The UBC Farm's drop-in volunteer program seems like a particularly good way to learn about food gardens without having to fork over lots of cash for classes.