The event is fortunate to enjoy the support of the City of Charleston and the town of Mt. Pleasant and their bureau of tourism committees. As a result there are numerous hotel choices at all different prices and levels to choose from.  Check them out here:
Please note that the weeks of Nationals are incredibly busy in Charleston. I would strongly urge you to make reservations very soon and if your team is unfortunate and unable to qualify cancel later. Also note that the Charleston Harbor Resort has numerous deals for competitors and parents/spectators and it is on site and excellent. It will be one of the very first hotels to fill up.