The fan amplifier is $120 on
Courtesy Parts. You can try asking a local Nissan dealer (I assume you went to an Infiniti dealer - maybe their prices are different for some reason), or just ordering from Courtesy Parts. The labor is indeed that simple - remove the glove box, disconnect the wiring harness, unscrew two screws, and installation is reverse of disassembly - there's a how-to with pictures
here. Maybe change out the in-cabin microfilter while you have the glove box removed, and if you're up to it
clean your blower motor as it's bound to be dusty.