I paid about $1800 USD per 3 week session, plus housing, meals, personal expenses. AUP doesn’t have a cafeteria/associated meal plans, so meals are your responsibility. I stayed in university housing for the first of the two sessions, then moved into an Airbnb for the second session. The housing through the university is slightly cheaper, but you have 1-3 roommates and the apartments aren’t as nice as what you can get for a monthly rental on Airbnb. My Airbnb was about $3000 USD (for a studio apartment in a good neighborhood), but it was last minute, so I’m sure you could get something cheaper if you looked farther in advance.
Here’s the program: https://www.aup.edu/academics/summer/french-immersion
You don’t need to be fluent in French to get a job there, since almost everyone speaks English, so a work opportunity wouldn’t be impossible to find. (You learn quickly anyway 
)
I took 2 years off from school after graduating and am going to college this fall. I didn’t use any specific gap year program, just figured out what I wanted to do and how to make it happen. However, there are pre-planned programs out there if you want to go that route!
The American Gap Association is a helpful resource, especially if you’re looking for a work/volunteer opportunity.
http://www.americangap.org/