I buy 5l stuff for £15 and dilute it 2:1 (Water: wash) Still works to -10C.
Neat is -63c which we don’t need here !
So really it’s £5 for 5litres which isn’t too bad
I dilute it a lot more than that and it still is spot on. I think I do it at around 5:1 and its still a deep blue, and never freezes or struggles to get rid of stuff on the windscreen.