There are a number of options, listed below in decreasing amount of pikeyness:
Camp under the lift in ADH. Free to do, can use the showers/toilets in the building next door. A lot of people do this so there's quite a good atmosphere too.
Camp in Allemont – Campsite is pretty cheap and you get to finish every day riding the end of the mega course. It's warmer at the bottomw of the valley but facilities in the town are limited. There's a small shop, bakery and a restaurant/bar. The downside of being down here is if you don't have your own transport getting up to oz en oisans at the start of the day for riding can be a pain. There are buses with trailers but they can be very busy and a bit of a scrum. It's a great place to be if you have your own transport though.
Apartment in ADH – Call the local tourist office and they'll be able to sort you out with whatever size and quality you want. We had one right opposite the main lift for four for a week. Cost us about £350 in total i think. ADH has decent shops and places to eat so living is fairly easy. The town is pretty quiet in the summer but the event has some evening things on to keep you entertained.
Hotel in ADH – Again tourist office will give you any number of options, prices etc (they speak english too).