2003 Corolla AC blower motor

2003 Corolla with 72,000 miles. Has developed a small "clicking" noise in AC fan (seems slightly worse when weather is very hot). Sounds kind of like having a card in your bike spokes, but is not very loud. My 60 year old Dad can't even hear it. Noise accelerates along with the fan speed. AC is still otherwise working fine. Mechanic says the blower motor needs to be replaced, but that it will not cause damage to keep using the current one until it fails completely, since it's a $238 job. Does this seem right to you?

Thanks! Andrea