SERF out at UBC has used computer equipment. Not sure about laptops, but they have older desktop systems.
Get there soon though; they are closing up shop for good (?) in mid-June. Their building, parking lot, and grassy knoll are already fenced in; soon they will be plowed over, dug up, and replaced by a new building. I've been watching the progress from my office across the street
BTW, SERF is the "Surplus Equipment Recycling Facility". Old equipment from UBC gets sent there to be sold for cheap. Not just computers but also furniture like desks, chairs, chalkboards, bookcases, and also old scientific equipment.