External flash set up for nikon d300?

What is a good, affordable external flash set up for a Nikon d300. I'm shooting BMX and skateboarding. Any help is useful I'm new to external flashes and I'm not sure what receivers to get and what else I need.

I shoot a lot of motocross and some BMX.

I do NOT use a flash when shooting these events because the race tracks where is shoot restrict the use of flash on the track. Shooting skateboarding is not as restrictive, so not a problem

I have a colleague who shoots X-Games and he uses a Nikon D40 because he can use shutter speeds faster than 1/250 second and still sync with his SB800 flash unit (mounted external to the camera on a light stand about ten feet away and synced using a Pocket Wizard. The D40 is unique since it can sync up to 1/1000th second. All other dSLR cameras are limited to shutter speeds of 1/250th or 1/200th second or slower.

There are other remote flash sync products and they all work just fine, but they are not compatible with each other. That means if you buy one Pocket Wizard and one Cowboy, they will not communicate with each other

Here is a link to a few choices you have.

http://www.amazon.com/...zon.com/s/

NOTE: Using a Nikon D300 in bright sun and using a remote flash, your highest shutter speed will be 1/250th second