Answer:
According to NYMag.com you can hire a Juilliard soloist for $300/hour, and a full orchestra from $2,000 in New York City. Terra Vista Strings in San Antonio charges $515 for a string trio for 1 hour, and $645 for a quartet. The Seattle String Quartet charge $750 for 1 hour for a quartet, and $600 for 1 hour for a trio.