There are some really good places to shop in Charleston!
There's a Tanger Outlet mall in North Charleston. There's also Citadel Mall and Northwoods mall. Don't forget to go to King Street in downtown Charleston. Louis Vuitton and quite a few high end boutiques!
I haven't been there in a few years, but Charleston Place hotel (right downtown on Market) had a promenade of nice shops. I've heard the Saks is closing--it's on King, but is pretty small. As others said, some great indie boutiques on King and other downtown areas. It's a walkable city so it's easy to get around. The market is fun.