I'd grant that, while not always $10, the price of a gram (usually the smallest unit sold, other than guys selling individual joints here and there) - the reason you don't see a lot of price fluctuation is becuase this is a bottom-end price. The markup is already huge - there is lots of market fluctuation for the people buying from growers and buying quarter-pounds and whatnot, depending on quality, quantity, market, etc..... but at some point, it's weed man. It's not worth someone's time to do a transaction for less than $10 (or similar) - even if they're buying at a much lower price.