Astro said:
why would you buy that?
buy a phottix odin instead.
ps: with the ST-E3 RT the sync time is down to 1/100s on everything except a 5D MK3 or 1D X when using radio.
otherwise you will have some shadowing on your pictures.
I am in the same boat as the OP. I'm really curious as to why inventory is so limited. I might end up buying a 5th 600EX if the STE3 isn't available soon.
I was considering the Phottix Odins for my 580ex IIs but in the end I'm glad I didn't because the 600EX' are so easy to use. The Canon system has a very significant advantage in that they are a closed system and don't require as much set up as an IR system or a third party RF solution.
I still think they 600ex' are a tad expensive but I'm a believer. I sold 3 580ex II and bought 3 600ex. Very shortly after I bought a 4th and am considering a 5th (since I cant find an STE3).