2010 rear seat belts are stuck.

I just purchased a 2010 Prius off of craigslist. It had a few issues that i have already fixed, air filters, fluids and exterior window belt molding. Typical stuff for a 5 year old car with 110k miles. I recently had some friends in the car and could not get the rear seat belt to unroll. It is stuck, locked in a fixed position.

My question to the Prius chat forum is: Are the rear belts interchangable between years and models of Toyota? I'm looking for the most cost effective way to fix the problem and am having a difficult time locating a 2010 Prius in a salvage yard. Local Dealerships want $150 for the belt.