The lens is the cheap part.
You can either use a standard video camera/DVCam or one of these:
http://www.panasonic.com/PBDS/subcat..._ag-dv1dc.html
As it has no lens it will last longer (the vibrations can ruin normals video camera lenses). You can get one shipped from the US for around £550 + shipping.
By the sounds of it scrutineers want everything bolted down quite tightly. Velcro wont necessarily pass all scrutineers.
Im looking at running one for the whole season next year....fingers crossed I can raise the sponsorship.