There is a place Just North of Wilsonville that stores boats and RV's. I think it's on the corner of Farrington Point Road and Hollands Chapel Road
Google Maps
(EDIT: The map points to Wilsonville, you need to follow Farrington Point Road north for a bit to find the actual intersection.)
As reference, this is on the North side of US 64, between Apex and Pittsboro. litterally 5-10 minutes outside of Cary. Very near Crosswinds Marina and also near Farrington Point Marina.
I don't know the price, I just see it every day on my way to work in RTP.