KYGunCo just dropped their price to $560 inc shipping, works out about 8 bucks cheaper than what I paid in the original link (which was still a stonking deal).
Got my Sport II now and very happy with it, great gun.
Thanks Armybrat, after lurking on this forum for a while and researching the Sport II for a couple of weeks, I decided to take the plunge and just finished ordering from kygunco. Including FFL fees etc. about $610. Now for some extra mags. I think I'll hold off on accessories until it shows up and I can shoot it first.
Just ordered one for $559 from Sportsman's Outdoor Superstore. Free shipping and no credit card fees, so it works out even better than the $539 + shipping in the OP. I'm a pistol shooter. I haven't owned any rifle in over 30 years. I've been starting to feel that it's my patriotic duty to own an AR before they're legislated out of existence.