Nikon camera and fisheye

Basically I'm after a good quality fisheye, an because I'm interested in skateboarding photography I think autofocus is a must? But I'm not sure what is the best option, as far as I'm aware there's some nikon cameras that have the autofocus motor built into the body itself? So would it be ok to get a manual focus lense an upgrade my camera? And anyone got any recommendations?

Strangely, I don't think Nikon currently makes an AF-S fisheye. The Nikkor fisheyes are AF-D and will only autofocus with a model that has an autofocus motor, e.g. D90, D7000, D7100. They will not autofocus with the D3100, D3200, D5100, or D5200.
So what to get if you have a Nikon with no autofocus motor?
That would be the Sigma 10mm f/2.8 EX DC HSM Fisheye Lens for Nikon
http://www.bhphotovideo.com/...EX_DC.html
HSM is hypersonic motor, Sigma's version of what Nikon calls AF-S.

You don't usually need AF on a fisheye because the depth of field is vast.
There are 3 types of Nikon lenses:

1. Manual focus - will not autofocus on any camera.
2.AF-S - will autofocus on any Nikon DSLR
3.AF-D and older autofocus lenses which don't have AF-S - will only autofocus on bodies with the body motor, such as the D90 and D7000/D7100.

So a manual focus lens won't AF on any body, but if you pre-focus on a manual lens, the huge depth of field will mean that just about everything is in acceptable focus, especially if you stop down to f8 or smaller aperture.

Sigma's equivalent of AF-S is HSM and there's a 4.5mm circular fisheye which would give you AF on any Nikon DSLR: http://www.calumetphoto.co.uk/eng/product//399-080k

If you are talking DX cameras, Nikon only makes one fisheye; the AF 10.5mm f/2.8.It will not autofocus on the entry level D3xxx or D5xxx cameras. But it is an outstanding lens - I own one.

Here is a review on the lens I have:

http://www.althephoto.com/lenses/fisheye.php

I guess the reason for not putting a focus motor in the lens is to keep it small, and I suppose Nikon figures anyone that would spend $700 on a lens would also buy a mid-level camera that had a focus motor.