I hope this doesn't fall under general sourcing, because this is more an observation than a sourcing post. I haven't seen a single legitimate listing on any marketplace for real lean. I've seen a few "homemade" lean listings, but thats about as close as it gets. A grams search doesn't yield one, either. Has this always been the case? Someone needs to step up and fill the void. Lots of money to be made on this from people who would resell IRL.
Codeine is so shitty. I feel like people only do it because rap. Even if it was for sale, that stuff is so expensive. Sorry for not answering your question but maybe you've never tried lean. It is one of, if not THE, worst opiate.