Is $600 to replace furnace inducer motor a fair price?

My furnace system is about 5 years old. I wasn't getting any heat and found error code 42. The installation company verified it's the inducer motor; the rotor seized. The technician was able to free it up temporarily, but it seized again shortly after their visit. The system is still under warranty, but the service provider quoted almost $600 for the replacement even though the part is under warranty. I am confident I can install it myself. I'm trying to decide between paying the company $600 or getting a used part and doing it myself. I'd really like to get a free warranty replacement part and install it myself, but that seems unlikely. It seems crazy to have such an expensive fix when the system is only 5 years old, and I haven't even paid it off yet.