Rebel Miniatures has some great Cop figures in 15mm along with civilians and rioters. As for scenarios, just raid some X-file episodes . One of my favorite ones was the fake aliens finding out there are real aliens !!
I am waiting for the exchange rate between the US and AUD to improve a bit. I really with Rebel minis and Khurasan had stockists in Australia or the UK, as there is some much that I want to get.