Through your club pro or golf galaxy or another retailer.
I just went through this process. The people at golfsmith have no idea what to do. To buy it from titleist is 90 bucks more expensive. It took me forever but i got the idea to ask golf galaxy to take my adapter off my original shaft and put it on the new one. Saves alot of money.
Please be aware that removing the adaptor does void the warranty although whatever shop removes the adaptor should stand behind their work.
We don't have an MSRP for shaft alone orders so we always recommend getting several prices - perhaps from your local pro and then from a retailer because they are free to set their own price for these shafts.
Cathi @TeamTitleist 1-888-TITLEIST