Originally Posted by tclune
There was a Sigma zoom, 50-150mm f/2.8 which has been discontinued (and had an even worse than Sigma's usual bad quality rep) that might be a good fit if you can find one that isn't misaligned. People who ended up with a good one really loved that lens. It is DX-only and light for such a bright zoom. It comes with a motor in the Nikon mount. FWIW
I have this lens, and it is a gem. I haven't had any problems with the lens, and it is well built and sharp. I bought mine from KEH for about $600 and it is my main indoor sports lens...I shoot volleyball and basketball with this lens.