I don't think that the cost of camping has gone up anymore than anything else.
In Ontario an average night in a provincial park with hydro, no water or sewer hook up, will cost around $40. Gas has dropped this last month to $4.35 a gallon or $1.15 a litre. Groceries cost us exactly the same camping as they would be at home. It would be hard to determine the cost of TT per night.
When we hotel we pay on average $ 140 a night for a hotel room, some have been $200-300 however. Meals out, 70 to 100 per day.
When we holiday we really don't question the cost once the decision has been made. We know roughly what a holiday will cost and then tuck away an extra weeks expense. We seem to manage to spend it unless we are camping.
After the initial output of money for equipment the actual costs of camping are quite low.