Yep Thing is, though, If you know the part number most of the semi independent parts guys will give you a reasonable price. It's extremely rare to find a filter ( lots of other things for that matter ) that suits only one application. Get to know what they are and hunt around.
Autobarn, Supercheap, Repco, all the same I reckon. In Vic I recommend making friends at Bursons, but I did that when the local bloke was Motorgear, now gone.
The chains see $$$$ when you mention LR. Find out where your local workshops ( not LR, just general workshops ) get their parts and then ask them. Get to know them well enough and you'll get trade discount. That should only be 10% GST these days, but you'll be surprised.
The most expensive aspect of regular servicing should be the oil. Never compromise on oil. But there are many reputable brands of filter. Mann and Ryco come to mind, but there are others.

