I've used Esposito's Ice in Morristown for years for dry ice. They are very inexpensive, and you don't have to buy a truckload of it.
www.espositosice.com
MAJOR POINT: When transporting dry ice in your vehicle, KEEP ALL WINDOWS IN THE VEHICLE OPEN until you arrive at your destination. Carbon dioxide buildup inside the driving compartment is not a good career move.
Klinker