I buy cheap Penns at Costco for my ball machine and never have an issue because if someone picks a couple of my balls, who cares, they are cheap and disposable. And if they cannot tell their ball from my balls, if they do not buy good balls which are different, or do not bother to search for theirs, they are free to pick up any one from my balls that they like. I do not care too much about keeping the integrity of my ball machine load. I have five 48-balls boxes of Penn sitting in my garage waiting for warmer temperatures, and all of them will end up donated to yoga studio where my wife takes classes or to dog owners by the end of the season. Cannot think about them as anything else than disposable items.
Some folks, though, buy balls of non-yellow color (brand selection is severely limited, though, but they come in a variety of colors, not just pink) or pressureless balls which come in, e.g., grey and yellow, as opposed to pure yellow. This helps with keeping their balls in check, probably much more than a difference in brand name or logo imprinted on a yellow ball.
And then, there are ultimately dead orange balls which actually can be fun to play at times
