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They're made by Jakks Pacific. I don't think most stores have them any more because the Jakks stuff has been phased out for TOMY who got the rights back to the merch.
You might still find them in the reduced stuff aisle though. TRU probably would still have them with the Pokemon merch on the action figure aisle, with Target having them on the back endcaps (maybe an aisle between the toys and outdoors stuff, but that's usually summer water toys) and Walmart usually has the aisle somewhere near the toys too.
If you're interested in having just balls in your collection, TOMY has snap open balls kind of like the old ones in the 90s that you could throw at like, those keychain things and capture them. They're not as snappy though, but they come in I think like 5-6 different balls, plus a TOMY figure. (the same sort of version of the figures they sell in the Pokemon Centers/Nintendo World Store)
I got one with Keldeo and a Master Ball.