The 94C draper head is built by Honey Bee, the auto float is an option and was not available initially. If you are looking for a used one, check to make sure it has that option. To have a dealer install it will cost you about $1,700 Canadian.
The 72C is a riged auger head that was built in Saskatoon at one time. It is usually half the price of a draper head from the factory. You might be able to find a good used one for about $15,000 - $20,000 for a 25ft. A 30ft will be a bit more.