The Open Jar Institute is one week in NYC, but it is $2,925 and the audition deadline was a while back. However, they do take online audition submissions if they have space available.
http://www.openjarinstitute.com/High-School-Session-I.html
Westminster/Rider is $1,825 but its two weeks. The registration link is still open.
http://www.rider.edu/academics/colleges-schools/westminster-college-of-the-arts/westminster-continuing-education/summer-camps/music-theater-workshop