Ballooning is expensive because of many reasons.
The envelope part of the balloon cost Thousands and only last about 400 hours, then you've got the basket, burners, fuel(vehicle and balloon), retrieve crew wages, vehicles, trailer etc. So the money is justified. Don't forget the Champagne!! Plus the fact that you need good weather conditions and the crews are normally working early mornings or late evenings in the summer for the cooler temperature for the balloons.
Try The European Balloon Company based at Great Missenden in Bucks 01494890301 a very good balloon company I used to work with.