Well, a band is good. But the first thing you do is rip it off and throw it away.
Can you do a ball that has an elasticated band?. If you pull the yarn from the centre, the elasticated band could stay on even while the ball shrinks?
If you put a lovely thing like a beaded stitch marker
on the centre yarn, so that people dont have to fish around in the centre to find the end, that would be beautiful, and make you unique !