Also might combine it with a factory visit as we'll be down in the Deep South anyway!
That would be the Rolls Royce factory then!

With regards to prices, a 3-day ticket this year was £215. If you want grandstand seats I think they are about £50 or £60 for each day (I take a chair and sit at the trackside).
I've never used the campsite or bought any of the various "hospitality" options I'm afraid so I can't comment on those.