Tell you what - we'll post free advice here for you and others to see. That's kind of how it works around here.

Does your budget have to include lenses, memory cards, software or anything else or can you spend that full amount on a camera body? In that price range for a fast sports camera, the best choice might be something used. If you're using an existing lens system it makes sense, of course, to use whatever brand of camera is compatible with those lenses. If it's Nikon, maybe a D1H is a good one to look for.