I think Eagle's Rest RV Park charges about $2.50 a day during the season. You might give them a call. The boats seem to be in a pretty secure area. They seem to have people checking on things pretty regularly. 800-553-7275
For 50 cents less, you could probably store it up at Gregg and Deanna Gudgell's place (D&G LTD) that's on Sawmill Drive (next to Airport Drive.) It's about 4 or 5 miles up from the harbor. 835-2977 That's where C-Farer spends the summer when she's not afloat.
Pat