A replacement mast is $11-$13. If you can operate a pair of pliers, it's a simple 5-minute DIY job. From the 9-3 FAQ:
How do I replace my broken Antenna Mast? Antenna Mast failures generally occur because people ride through the carwash with the antenna up. Once the mast is bent replacement is the only repair. As long as the antenna cord is not broken, repair is fairly simple. Simply remove the 17 or 18 mm nut off the antenna assembly top and pull out the portion of the antenna mast that still remains in the assembly (You may have to turn on the radio when attempting to remove the old antenna mast). Slide the original sleeve over the replacement mast and place the nut over the mast and insert the corded portion of the antenna into the antenna assembly until it reaches the bottom. Have someone turn OFF the radio and slowly rotate the cord clockwise until the corded portion of the antenna is pulled into the antenna assembly. Slide the mast all the way into the assembly and install the nut and tighten slightly! DO NOT WORRY if the mast does not go all the way down at first as it will adjust itself after turning the antenna on and off again.
NOTE: Remember to keep the silver sleeve that goes around the lower portion of the antenna mast as you will want to use the original sleeve as opposed to the one that is supplied with the replacement mast! (The ones that come with the replacement mast are often too thin and will not secure the mast well enough!)
NOTE: There are occasions where the antenna cords break off and will not allow the replacement mast to be pulled in by the rotation of the antenna gear assembly. In this event you will have to remove the antenna assembly and disassemble it and manually remove the broken portion!