So, the house it was filmed in and suburb they were supposed to be from is “Winnetka” which is a northern suburb and where a lot of exceptionally rich people live. Houses in that area go for millions. Though, it’s possible they were a house broke family. The mom was also supposed to be a fashion designer and it was the uncle who paid for the Paris trip.
Edit: house is currently pending sale for over 5mil, and pictures show there’s a full basketball court and home movie theatre inside. Wow
The really rich uncle paid for it. In the opening you learn their niece lives with them and her parents are in Paris. I believe it’s their ridiculously expensive house in the second movie that is being renovated in NYC as well.