OP, there is also a Premiere Classe hotel at Bussy-St-Georges (or Georges-St-Bussy, I will never learn the proper name), which is a 10-minute drive from DLP (Take A4, direction of Paris, exit 12, right at the Exit), there is a RER nearby.
Another cheap option, but you need a car, is a Bed and Breakfast at Villeneuve-le-Comte. My mom and I paid 57 EUR per night for the room, and this included a wonderful breakfast. I know they also have a "family suite" for more than two people. It's very close to DCR.