Les for Z 50

So I’ve got a Z 50 right and I’ve only got 250 mm telephone lens. i’m mainly use this camera for airshow photography but I can find that the lens isn’t sufficient enough for high detailed photos. Furthermore, at other places like airports, I can’t get sufficient enough quality photos due to the lack of zoom. I want to get a new lens for it, but I don’t want to pay the mind blowing prices. Is there any like a third-party companies I could buy from cost about £200? I’m looking for a lens that’s about 350 mm.