I’m using the same.
Mobil 1 and a K&N HP-2004 at 6 month/7500 mile (12,000km) intervals.
The K&N filters are very good. But I agree they are over priced.
However if you watch for sales at Canadian Tire you can get a good deal.
For instance…this week I picked up the K&N HP-2004 for sale price...