you could. its about $160 per side (you can get a discount through sewell though being a CL member)

http://lexus.sewellparts.com/oem-cat...450h-2008.html

 

One way to deal with it from a maintenance perspective is to run a piece of fine sandpaper a few times between the belt and the metal piece through which it travels at the B Pillar. Dirt accumulates on that area, affecting the ability of the belt to retract as it should. Obviously, this will not repair the damage you have but will prevent it from getting worse or mitigates recurrence of that damage if it has been replaced.