You are right about the short OCI I run, mainly for fuel dilution and also convenience, but probably a waste of good oil and filters.
This time I paid around 6,50€ per liter for this Petronas oil...car needs 3L so it's not an expensive OCI, with filter cost a bit over 25€. Even if it's twice a year, it's still decent.
For comparison the Total 5W40 in my sig is ~3€ per liter when bought online, SHU 0W40 around 4 (add shipping but that's still very affordable).
M1 0W40 would be like 9, and the 300V is approximately the same price as M1, unless you found discounts
The Purflux LS489A filters cost around 5€, they have a silicone ADBV (not that its useful for this car). I bought a bunch of Fram Ultra XG9688 that I'll use in the future with this car, when I'll run out of Purflux.
I can only speak for my country, but I don't think we have the culture of cheap oil change here like in the US or Canada, most dealers or even quick oil places charge way too much for badly executed oil changes...I prefer to do my own more often, keep a clean engine, and also have cars "always ready" to go for a long trip. My family and friends are not getting younger, and we are pretty far away from each other, I want to be able to leave right away for 2-3000Km without questionning if the car will make it or not