OG Games has become my online store of preference for all miniature purchases. There are two simple reasons behind this:
1. Competitive prices
2. Customer service - You'll be told when items are out of stock and the expected delivery times are accurate. If you have any queries you can just fire off an email or jump on the forum and you'll get a quick response. Anything not in stock you want, try asking and they might be able to get it for you.
With service like that I see no reason to go elsewhere.