in-cabin microfilter 2001 i30

[rubs]

Hi,

I recently bought a 2001 infiniti i 30 having about 45k mileage and checking the maintenance schedule. I change the engine oil and filter but was told that in-cabin microfilter can only be change by dealer and dealer is charging 120$ to do this.
Is in-cabin microfilter can only be change by dealer?
Do we need to change in-cabin microfilter every 15k miles? (it was last changed at 30k)

Thanks
--Rubs

[nhaven]

http://www.innerbean.com/housecor/cabin_filter.html