Well, 30 shillings, mind. Not a penny less.
5 seconds sound clip from the Chitty Chitty Bang Bang (1968) movie soundboard.
You can hear this line at 00:08:43 in the Blu-ray version of the movie.
Quote context
[...]
- Please, you can't sell our lovely car to that nasty man.
- Well, I'm sorry, children, but I'm afraid I already have.
- I know! Daddy will buy it for us. Won't he?
- Promise you won't let her go until we come back.
- Well, 30 shillings, mind. Not a penny less.
- Well, that's a clever thing to do!
[...]