I've seen these on Flea Bay but don't know if anyone actually buys them.
Just for the 1234567 digits there would be 7! = 5040 possibilities. Same for 0-6, 2-8, 3-7 and 4-0. In all we're talking about 25,000 possible serials or 1/400. 2.5x more common than a lowly 4-digit radar note.
As far as the zero counting as a 10, Charlton does recognize 4567890 as a ladder. Some might object to that. I bought a bunch of US notes with 34567890 serials for pretty cheap only to be told that those were not real ladders.
To each their own.