I got 2 new turnigy packs, 5s 5000 mah from hobby city (20C). 50 bucks per pack and 37 bucks shipping and of course no tax. So 137 shipped from China. I ordered them on a Wednesday so they did not ship until Thursday and received them 2 days later on Saturday morning just in time to race! I checked the internal resistance of each cell (thanks to my good old cellpro 10s) and they are all 1-1.2 milliohms. Getting the same 2 packs in the US would probably cost almost 2-3 times as much.
Edit: Oh and one other thing, I own a couple trakpower lipos, paid 105 for each one (great batteries!). Brand new, the internal resistance of those cells was around 4-6 milliohms. Just thought I would add that in.