About the equipment, there is 2 kind.
first it is the camera body. The better camera body has faster frame per second ,more responsive, more auto focus points for precision composition.
In Nikon line, it will be D90 or D300, in Canon line, it will be 40D or 50D
for extreme best, Nikon D700, Nikon D3, Canon 1d mark iii
for the lens, it depends on where you usually sit and what style do you like, I usually sit on the floor under the basket. My style is tight shot.
So i use either 50mm f/1.4 or 70-200mm f/2.8
Notice the max aperture lens that I choose. It serve as 2 functions
1. It is for low light condition (so i can bump the shutter speed up to 1/640 without having to increase iso to the extreme).s
2. It is to isolate foreground (athletes) and background.
If you sit on the bench, then try to get closer to the field, and 70-200mm seems like the minimum length. 300mm f/2.8 is good but very expensive.
If you plan to sit on the floor then getting 50mm f/1.4D is a nice deal, unfortunately when mounted in D40, it can't auto focus. The new version, 50mm f/1.4 AF-S is more expensive ($400) but the problem with it is (based on test) the Auto focus is not fast either.
So if you stay with Nikon D40, I suggest Sigma 50mm f/1.4 HSM ($450) (only if you are sitting under the basket.
But if not then 70-200mm f/2.8 either Nikon 70-200mm f/2.8 VR AF-S ($1600)
or Sigma 70-200mm f/2.8 II HSM macro f/2.8 ($750)
Other Nikon telephoto zoom lens Nikon has is 70-300mm AF-S 3.5-5.6 ($600) (Not recommended because it is optimized in the wider end. 200mm and above, the quality start deteriorate. Beside, you won't feel significant differences than what you use right now because the max aperture is the same f/5.6
So, yes, it is expensive to get quality basketball or indoor sports pics where the light usually is very limited.
http://www.radiantlite.com/uploaded_ima ... 779501.jpg
this one is using canon 40D and sigma 50mm f/1.4 HSM
http://i269.photobucket.com/albums/jj74 ... ure126.jpg
this one is using Nikon D700 and Sigma 70-200mm f/2.8