Here are some Amazon deals on indoor pickleballs. Compare these prices to the $12.99 for a 3-pack of Onix Fuse indoor balls. I have about 100 outdoor balls, so I don’t look for deals on them.
Gamma Sports Photon Indoor Pickleballs, High-Vis Optic Green USAPA Approved Pickleball Balls – set of 6 for $12.95. I have played with these indoors and they are a good ball. From my experience, this is a great price for a popular ball.
A&L aupinelife Indoor Pickelball Balls – set of 6 for $9.78. I ordered these balls a few days ago and used them indoors on Monday. These are the balls used by “Das Rec” in New Braunfels. They work perfectly fine.