It's quite cheap to fly to Paris CDG then get the TGV to Le Mans.
This year I flew from East Midlands to Paris for about fifty odd pounds return (inc taxes etc) on BMI Baby, then got the TGV first class to LM for £35 and came back on a slower "Ten" service for £25 (no TGVs at 4am!)
Due to none of my friends being able to make to full trip this year, I went down for qualifying on Wednesday and Thursday and came bakc on Friday.
I got the tram from Le Mans station to the circuit on wednesday, camped in my small tent in an unmarked corner of KN wednesday night and headed back to Le Mans train station on foot after Thursday qualifying (the trams had finished running by then) for my 4am train back to Paris.
It was well worth it for my annual fix of Le Mans, especially down at the awesome Arnage (although no fun walking back from there in the dark) and I watched the race at home on a TV projector I borrowed.
Hope to be back for the full week+weekend next year.