Not paying gringo prices in Mexico

Okay,

So I will be in Cozumel, and I am planning on going to the same spot, where I got some bud last year, it's right near the cruise ship dock, and there's dealers out there always hitting up the tourists.

My question, I know that in Mexico, a gram of blow usually costs about $10 in the "tiendas" that have been set up by the cartels (they are little stores where they sell drugs, but they don't have them in Cozumel). How do I not pay the gringo prices? They could be jacking it up to 20 or 30 a gram maybe? I know that negotiation is key in the brothels when paying for services, I try to never pay full price there. Maybe I can get a better deal scoring some from the bartender in the brothels? Or, are my chances of getting a good deal just the same in the more tourist areas? Sometimes, the shopkeepers offer me weed, but it's usually crappy bud when I take a look at it, so I usually pass. Heck, I would be okay paying 20 for a gram in Cozumel if it's good. I know that the prices increase the further away from the source you are.

I speak decent basic Spanish, took 3 years in high school. I am thinking that I just need to haggle a little bit, just like negotiating for prostitutes.

 

maybe these aren't questions you should be asking in public forums while giving away so much personal info about yourself and your planned activities. good luck to you and stay safe. make good decisions.