B&H Photo has the 6-core Mac Pro in stock as I write this. See the buttons on my Mac gear page, and thanks for clicking those buttons to buy. Applecare at B&H is also a much better deal than at Apple.
What do you get for the same price? Six CPU cores at 3.33 GHz in the 2010 model, 4+1 internal drive bays, PCIe slots, proven design. For the same price, the 2013 model has 4 CPU cores at 3.7 GHz and a small internal SSD and no internal expansions, but has fast GPUs (yawn for most tasks) and USB3 and Thunderbolt. Which one might prefer depends.