Been waiting for this one...that's $9.99 in the US, I think this is the lowest price the GOTY edition has ever been. It doesn't include everything from the Season Pass, but you still get a lot - Mechromancer, Psycho, etc. Here is everything included with this edition:
I've never used this site before today but I just made the purchase and redeemed by Steam key without any issues. The page says Mac but Borderlands 2 is a Steam Play title, so you get both Mac & PC versions.