See your other post on labor cost - can run minimum service charge to maybe about twice that for labor that depending on how accessible the unit is - some right at the front, some tucked away in a hard to access place. Occasionally takes 3-4 hours for a few very hard to service units or ones that have been installed so the correct panel cannot be removed to access it because of too limited a clearance around the unit, so that could drive the labor cost up to 3-4 times the minimum service charge in rare cases.
The blower fan itself sometimes is swaged to the motor shaft and not designed to be changed separately, so in that case the motor replacement costs you found applies.
Sometimes the blower fan is integral to a housing that has to be replaced as a unit - for typically about $150-300 for that unit, plus labor.
Other times the blower fan or wheel can be removed and replaced, commonly around $50-150 for the fan itself plus labor, depending on brand and if using OEM part or after-market.