Well, what you can do is set some aside for yourself. Sell off whatever people want from you, give them some nice prices so they'll come back to you. For $120, you're getting a pretty damn good price if it's good stuff. One ounce is 28 grams.. you're basically paying a little bit over $4 a gram. Let's say you sell 20 grams for $10 each. That's $200 bucks, and you still have 8 grams left over. You just made $80 profit, either sell the rest of the 8 grams or smoke it. Rinse and repeat.

Also, whenever you do smoke with friends or whatever, tell them to fade up a few bucks.