It's very rare for the actual starter motor to fail. It is much less rare for the clutch (drive) to fail. Rather than spend $400 for a starter assembly, spend $100 or less for a replacement clutch.
If you've had issues with the starter drive kicking out or making grinding noises, I'd suggest you pull the outer primary and closely inspect the starter pinion gear and the clutch ring gear for damaged teeth.
Models from 2007 until 2010 that still have the original compensator, or until 2011 for TC96/TC103 Touring models, can have starter engagement and kickback problems related to the POS compensator. If that's the case, replacing the starter drive or the starter assembly won't be a permanent fix until you replace the compensator as well.
Jerry