What are your aspirations? Just to keep it a hobby or go further?
Honestly, I'm not entirely sure. I guess there are two schools of thought here:
The optimist: make a hobby your business and you'll never have to work a day in your life
The pessimist: make a hobby your business and you'll ruin your hobby
That said, I really do love photography and I'm probably willing to go through a lot of crap to be able to do it all the time.
The Sigma 70-200 f/2.8 is dead cheap compared to the Nikkor and not that much worse.
True, however, the Nikon 80-200/2.8 is not much more expensive than the Sigma 70-200/2.8 and is much better. I tried all three lenses mentioned here and, money no object, the Nikon 70-200/2.8 wins hands down (obviously). Throw it back into the equation and the 80-200 is the clear winner, in my opinion. The Sigma is noticeably soft and has CA issues.
You and BCS will disagree on this, but I see far too many reports of miscalibrations with third-party lenses and do not feel like taking the risk of having to wait a month or longer to use a brand new lens. You also never know what forward compatibility Nikon may be already building into their lenses. Yes, in a better world, the big names would be (required to be) publishing their specs.
I am however of the opinion that buying nice lenses is far more worthwhile than upgrading the body. I know your body is somewhat of a limitation seeing as it will only work with AF-S (at least I think this is the case) lenses...
I agree, which is why one of the main reasons I'm considering the upgrade: with the ability to use AF-S
and AF-D, there are a lot more options available for good and relatively affordable glass. Better control interfaces is the other main reason.
...but what about the 80-200 or 70-200 AF-S?
The 80-200 AF-S is about as easy to find as a unicorn and I think the AF-D is better value for the money. The 70-200 AF-S is more money than I'm willing to spend on just about anything other than a car
I went with a lens that was aesthetically an absolute dog, it may not be pretty but optically it's fine and it was much cheaper.
Which lens was that?