I have seen them in the filter catalog at the local shops but haven't found any on the shelf. I would probably buy it from Rock Auto sicne they seem to have all the other stuff for my LS. I think the filters are about $20.
The filter is located under the hood against the firewall on the passenger side. It is under the black plastic cowling running along the bottom of the windshield. There are several plastic buttons that hold the cowling down. Mine has a center button in each big button that needs to be pushed down and then the big button lifts up. Looks like a bullseye about the size of a quarter. You will need to lift all the buttons on the passenger side and some on the driver side.
Under the cowl, is a flap that has a couple latches that need to be pulled a little to let the flap flip up. The filter is down under the flap and comes right out.
If it isn't too dirty, I would just blow it out with compressed air.
You will need to reset the "change AC filter" message. On my car you get into status mode, and when it says change filter, push reset and then push and hold reset again for a second.
There are also some filters under the seats that need to be replaced once in awhile.
Easy job.
Good Luck,
Jim Henderson