We all have gone through some sort of rip-ff using MJ in our times, big or small. There are people just like that and you just have to move on past them. Getting revenge will only piss him off, then It'll just go back and forth until someone gets arrested or killed.

Never buy from this person again. Next time you get a new hook-up, just either take it, or leave it. I know if I was a dealer, honest or not, and someone demanded that I give them their bag first so they can weigh it, I'd tell them to fuck right off.

There are honest dealers out there, you just have to filter through the crap before you can get to them. If the bag doesn't look/feel like an ounce, then don't buy it, simple as that.

Peace.