It is about 8k I would have thought, I know the UK price and it's about there although a bit more.
It is a cheap way to get to 800, yes. But for that amount, you're better off going with a camera manufacturer's own brand 300/2.8 and matching converters. Allows you to get to f2.8 at 300mm, f4 at 420mm, and up to 600/5.6. You lose a bit of reach but will gain better build, better optical quality as some focal lengths, and also the not-to-be-sniffed-at portability and size factor.
If you're struggling with weight then I really wouldn't touch anything other than the AF-S II.
It is a cheap way to get to 800, yes. But for that amount, you're better off going with a camera manufacturer's own brand 300/2.8 and matching converters. Allows you to get to f2.8 at 300mm, f4 at 420mm, and up to 600/5.6. You lose a bit of reach but will gain better build, better optical quality as some focal lengths, and also the not-to-be-sniffed-at portability and size factor.
If you're struggling with weight then I really wouldn't touch anything other than the AF-S II.