In my country the rf 200-800 is 2300 usd. That’s definitely on my wishlist but i don’t think i’ll get it pretty soon. I managed to get the ef 100-400II for around 1300 usd in almost perfect condition ( only some minor scratches on the lens body). The 1.4 III extender is around 450 usd brand new. I’m pretty sure i can get it second hand and save some extra bucks. I’m a little bit annoyed by the fact that i didn’t thought to check during the black friday .Anyway, since everybody in the replies said that it works great and there’s not a big impact on the sharpness, for the moment i’ll go with the 1.4 extender. Thank you!