We spend a fair amount on a steel building with a concrete floor. While I can't cost justify it versus off-site storage, it was worth every penny to us. First of all, as others have said it adds value to your property so when you sell you should get at least a portion if not all of it back. Secondly, the convenience of having our AS at home far outweighs the cost. When we start getting ready to go camping I can simply walk out to the trailer the day before and turn the fridge on, Then we can load the trailer at our convenience. I also find it very nice to be able to wax it out of the hot sun and in my own time frame. I'd do it again in a heartbeat.
Dale & Jane
2018 Flying Cloud 19
2003 Dodge Ram 2500 Quad Cab Diesel