I think Ann's classes are $125 for six weeks (six weekly sessions). Ah, scratch that, it's gone up a little: $140. See her page at
NoseWork.ca - NoseWork.ca
Ann is an amazing instructor - she loves all dogs, and works entirely on the philosophy that it's the dog's game, not ours, and above all, this sport should be FUN for the dog, so there's no great expectations, and no pressure. As noted above, I've done it with Taffy, who's going blind, and she's had other blind dogs in her classes before. It's good for older or less mobile dogs as well, as it's very low-impact (no running or jumping), and it lets them work their primal hunting instinct.