so target has headphones on sale that are usually about 25 bucks but today they are $9.99 and it's the last day of the cell how many should I get?

if it is blutoth you cant own more than 2 at once,the battery need certain charge and discharge cycle in period of time to maintain in good shape as owning too many headphone end up left some left unuse will degrade the battery.

3 pairs if they're good ones

Three that way they will last you a year four monthes apiece they should last😁