Grow your own. Scoring weed isn't worth associating with crackheads. But seriously, our site etiquette asks that you not discuss other drugs in non-medical forum sections.
The best way to find a reliable and professional-acting connect is the same way as getting a nice girlfriend- go out and join activity groups that do things potheads like, like kayaking and hiking and pottery and organic gardening and surfing and all sorts of outdoor hippie-ish activities. Give it some time to get to know your crowd, and eventually someone will break out some green and at that point, it's not impolite to say, "Oh man, I really miss having access to this stuff, if you ever have any extra that you want to get rid of, I'd be SO happy to hear from you and hang out" and give him your number. Do that a couple times and someone will eventually offer you some help. But, just like in dating, don't act TOO eager, because that is bound to freak people out and give them that narc vibe.