I came to Portland a little over a year ago and was in the same boat. All I can tell you is that you shouldn't listen to the websites that tell you to go to places like The Waterfront to get some. Your best bet is just to meet people who share common interests and eventually it'll find its way to you because it seems like over half this city smokes. You need to just get on board the OMMP train, but you might have to take some time to establish a medical history, that is if you have some sort of qualifying condition. Oregon is harder to get a card in than Cali, but I have a friend who got his for heartburn(the chronic pain associated with G.E.R.D. specifically).
As for street prices, I have no clue. Everything here is so about the MMJ scene that anyone who seriously enjoys pot has found there way into it, be it as a Caregiver/grower or patient. Good luck man, seriously. Being new to an area is rough, especially when you feel like everyone around you is smoking pot but you just can't seem to find it.