Sound advice, benagain.

That being said, I've always found this method effective: Make a sign saying "I need a drug dealer" and walk downtown holding this proudly over your head. You're bound to run into someone.

Seriously, if you have friends in town, it always helps to ask them if they know anyone, or just be really observant when your out in public. If you see someone that might be really high or about to smoke, go up to them and ask away. You've got nothing to lose at this point, right?