I'm another cheap cat sailor, but a lucky one. I pay $0 per year for year-round mast-up storage right on the beach, with the Gulf of Mexico 125 sandy feet away. It's a "vacant undeveloped lot" with restrictions that pretty much keep it from being developed. I leave my Cat-Trax tied up under my boat, and have a cinder-block sunk about 8' deep in the sand with a thick nylone rope coming up to tie my boat down with.
There are 3 other active catamaran sailors that keep their boats there, and 3 fairly abandoned cats. A lonely Escape that belongs to some friends of mine also sees frequent use.
Behind the sand dune that my boat sits in front of is a house who's owners only occasionaly use. When they are not present I can park in the driveway, and even use the hose to clean up a little when I'm through sailing. Two blocks south of my boat is the Sandbar Restaurant, which has an open-air deck and good food at a reasonable price for lunch.
The only caveat is that you have to sail your boat to the beach- the beach access road that ends a few yards from my boat has posts which prevent vehicle access. I suppose a couple guys could pick the boat up and over the posts if they were determined enough...