Sure there is, take the daily rate and multiply it times the number of days in the month
Now, on the serious side - this is the first year they did not offer "Winter Settler" rates, which was the Disney version of a longer stay rate. While any savings is good, the time I figured it out it was only an additional 10% off the value season rates. The only discounts you find now are AAA, Florida Resident and annual passholder - but even these are limited in the number of sites avaialble on any given night.