WGTShamWow: There is a feature that was implemented to allow you to purchase a ball on the last hit of your last ball but it is currently a little buggy and should be fixed soon, so may not pop up on the last ball.
Being precise, the new message "last shot on ball, purchase more!" appears with every ball, even if there are some more left.
By chance, this bug is good for the programming party - why?
Homi soit qui mal y pense ;)
P.S. Thanks Mr. S for dropping the former florid text.