I am fortunate that I can buy almost anything I need from a couple of local independent nail supply stores; you should see if there's some in your area. Online, you can find OPI GelColor (and a lot of other brands) from Nail Tech Supply - http://www.nailtechsupply.com/cart/opi-2?cat=901 or Beautywest (which also sells on Amazon) - http://www.beautywests.com/GelColorbyOPI.aspx
I found a local store in SF which i'm going to check out this weekend! pretty excited! going to "nail polish heaven"