Inexpensive and Charleston really don't belong in the same sentence. We kept our boat
at the Charleston Harbor Resort for a year. Nice place convenient but pricey. How tall is your mast
? If you can get under the Ashley river bridge there are some options. Dolphin cove comes to mind. If you need to step the mast at a yard City Boatyard will probably let you stay at their docks for a few days after stepping. Cooper
River Marina may be what your looking for again not sure on the prices. City Marina is super convenient but again pricey. You can anchor
just off the marina and park your dink for $5 bucks a day. Just beware that if the current
are at odds you will sail on the anchor
so give yourself plenty of swing room. Hope this helps!