The AK-74 round (5.45) is similar in performance to the 5.56, just a tad less powerful. The AP ammo pops up fairly often; have not seen any massive performance difference between the AP and normal jacketed rounds, but then again I am not shooting engine blocks or kevlar!
I am feeling fairly confident that the Federal gun control push is about to collapse under its own weight in the next month or so, and then the prices for 5.56 and 7.62 should hopefully come back down to something a bit more sane. I have had a little luck recently finding ammo, but its still damn spotty and expensive.
What do you think of the Waffen Werks I linked to, incld price? (has lots of mags, which is a big point to me right now)
http://www.gunbroker.com/Auction/ViewItem.aspx?Item=333219734