I'm just looking at 9mm and made a
Google Docs spreadsheet you can look at using these vendors.
Hunters Supply and Rim Rock both wanted me to create an account and login which I just wasn't going to do.
In 115 MBC is the cheapest by getting to as low as $0.0640 per with 6000 shipped. Although even if you just do 500 they are still pretty cheap at $0.0655 per.
In 124/125 ZCast is $0.0552 per starting at 2500 shipped.
In 147 ZCast is $0.0585 per starting at 2000 shipped.
-Mike