Possible solution; either the individual store or the company who makes the price tags have an app to use while you shop. You pick up the item, you scan it, you put it in your cart. The price you scanned it at is the price that is applied to your total bill. Any changes post scan dont affect you.

Me seeing this comment

Actually, looking back I believe the other Ditto was a boy form, which could mean its customizable. So let's make it #DittoKidforSmash. No reason to be exclusive.

And multiple Ditto kids were also shown off so there are options for various alt skins as well!

There were so many Pokemon shown in the trailer, and who knows how many more there could be beyond that. So many move options!