The Musto example the OP gives is basically a Derby tweed. I can get good ones in my local Farmer's Supplies shops for far less than the £400 they are asking for that one, though it wouldn't be a stretch material.
They are tough as old boots as Scottish Steve says! Mind you, my understanding of a "Sports Jacket" is more a tweed blazer/suit type jacket. The jacket the OP talks about I'd call a shooting jacket, as Musto do. I love my proper old Harris Tweed sports jacket! Not a Mr Haggas offering I will add!
Try everything in life except incest & morris dancing - Guy Warrack (1900-86).