if you don't mind waiting 5-6 weeks for it to ship from overseas, there's a site called BangGood.com a lot of us order from. They seem to have the best prices but it does take a while for them to process and the item to arrive to the US. I initially got some cheapy antennas from them and I'm having all sorts of trouble, I'm integrating advising to not skimp on antennas into all my FPV advice from now on. I've just ordered an antenna bundle from fpvlr.com
otherwise there's tons of other vendors.. just some random ones: Atlanta Hobby, Hobby King, Helipal, Florida UAV.. Amazon.
There are FPV kits all over the place if you want to just buy one (I actually liked building and installing it all myself)... the KumbaCam kit seems popular but if you google phantom 2 fpv kits you'll see tons.