Heres the official web site with ticket prices - in English
24 Heures du Mans − Official Website
You can order tickets and collect them from the official office at the track - this is worth doing if you want parking/camping in a specific car park/campsite. Dont forget to get a parking ticket for your car!
GENERAL ENCLOSURE
WEEK € 71
Ticket valid all of race week and also on Test Day (9th June). Ideal to make the most of the 24 Hours of Le Mans, with this ticket you can combine Test Day and race week; 16th to 23rd June. It includes the two practice sessions (19th & 20th June), pit lane visit on Friday, and the whole week-end.
GENERAL ENCLOSURE
SUNDAY only € 45
From 6am on Sunday you can come and see the closing hours of the race, finish and podium. This ticket is valid on Sunday 23rd June, you can also attend the Test Day (9th June) and breathe the unique atmosphere of the final hours of the race and the emotion of the podium ceremony.
HERE is a pdf with maps, parking ares and ticket types
http://www.24h-lemans.com/wpphpFichiers/1/1/ressources/Pdf/2013/24-heures-du-mans/plaquette_billetterie_24_heures_du_mans_2013.pdf