Don't think SB600 comes with a AS19. From my knowledge, only the SB800 comes with it.
That's explain the price different between the SB600 and SB800...
i. Lower flash power, guide no. GN26 vs GN38
ii. No Diffuser Dome
iii. No Colour Gels
iv. No AS19 Stand
v. No 5th Battery Support
vi. etc, etc, etc
That's the reasons why I always ppl to get the SB800 instead. Cos it is always the end results for almost all nikon users to either get the SB800 or upgrade to it ultimately, so why waste necessary $$$ to own the SB400/SB600 then upgrade later?