RJ,
Mid size dozers use about 80 gallons of fuel a day. So the daily cost of a dozer has gone up by at least $120 since fuel prices doubled, or about $12 per hour. In real world, the cost charged has gone from $95 an hour about five years ago to perhaps $125 per hour now.
If a dozer is used for 8 months at 6 days a week, that only adds $25,000 to a course. (per dozer) The real price increases are in delivery, plastics, and reimburseable expenses for the worker getting to the course.