I am not sure it is possible to venture a guess as the two key factors are unknown. The first is how well maintained was it before you bought it and the second is how much use you plan to make of it once you get it on the road.
My daily operating cost is about $50 for campgrounds, fuels and routine maintenance. That is over a 7 month trip where we crossed the country and back driving a little over 12,000 miles in a the coach in the signature. Our gas unit cost a bit less per day in 2011-12 but fuel was cheaper.
This is my experience spending about half the time in commercial campgrounds and using many free resources (WalMart when appropriate)and discount resources for the rest. Also that is high mileage, but you still need to figure on changing the oil 4 times a year in a gasser and once a year in a diesel even if you don't move it. Tires last from 5 to 7 years and are not in the operating numbers nor is depreciation or any other expenses such as mods you choose to do or have done and the "stuff" or toys that make RVing fun.
Storage depends, I pay $55/month for a storage space in Rochester whether I use it or not. I was just quoted $160/month in the LA area for fenced outdoor storage with no electric. I have seen as much as $400 for full serviced indoor storage.