I bought 4 600's from B&H when the price dropped from $630 to $600 (last July). Before the return period had passed, the price dropped another $20, and -- upon my request -- B&H credited the net $80 back to my charge card. Each shipped with a 4-pack of Pearstone NiMH AA's and a 4-AA charger. Very nice.
I've seen the price drops since my purchase, but it hasn't bothered me a bit, because I've been using and enjoying them ever since. (I also sold 3 580EX II's and a 420EX at very good prices upon receipt of the 600's, so that helped a lot.)
What a huge improvement over the 580's, especially in a multi-flash environment. So easy to set up, tweak and signal.
Personally, I wouldn't buy a ST-E3-RT, since it doesn't have an autofocus assist beam. For the moderate price difference, I much prefer my extra 600EX-RT, instead, since it can perform double duty.