Campground costs per month or longer?

[snowbunny]

We are still working and never stay at a campground for more than a week but are trying to plan for our extended stays when we retire. Can you give me some idea of what the average cost per month would be at places you stay? I am not interested in slums or in RV Paradise Resorts but good clean quiet parks with decent sites. So far we have paid between $30. to $50. a night but how much would that change if we were getting monthly rates?

Thanks.