Hmmm probably too late in the day to achieve much that is cheap and close by. Try the campsite at Spay, I think they have chalets or statics, it's a municipal so contact through the Mayor's office.
I'd ring the Le Mans Tourist Office and ask them for some pointers as to what availability you'll find.
A friend of mine reckons for the 24 he doesn't book hotels he just turns up and trawls round the Brit Hotel, F1 etc. and usually finds a room - might be worth just turning up if you're brave....
