Check out these guys..

www.hobbycity.com

They have some great deals on lipos/motors/ESC's... The lipo prices seem almost to good to be true, but there are a bunch of guys on RCU that say the batteries are great.. Less than 1/2 price of a thunderpower equivalent..

Also, if you want to see how different components will "play" together, check out www.motocalc.com . You can use their program for 30 days for free.. has an incredible database, and it will tell you if your components will work together and where the most limiting factor will be.. If you enter in your aircraft data, it will predict flight performance, static thrust, battery duration.. etc, etc, etc.. Awesome program and worth the 30 dollars if it saves you one fried ESC from a bad choice!