Start here:
https://www.facebook.com/groups/2317661623/ and here to find the locals. We have a monthly coffee meet so you are always welcome to come out and chat us up.
As far as buying parts, at this time everything that comes out of the states is expensive, but shipping isn't too bad if you send your packages to Blaine, Sumas or Pt.Roberts and then go down and pick it up yourself.
Finding parts for the AW11 is tough because of it's age. I would recommend that you become part of every MR2 forum, or FB group that you can. Other than that it's nice to have a buddy that works at a dealer parts counter. The two sites that you mentioned (esp. Twos'r'us) will have the most of any aftermarket site. The only others that come to mind are
sv3power.com &
matrix garage