Amazon has Adjustable Hand Grip Strengthener, 2 pack on sale for $8.99 w/ coupon code QGVDWWDP. Regular price is $11.99.
This looks like a great price for a good quality grip strengthener. It’s a 2 pack.
* Resistance adjustable: 22-88 Lbs (10-40kg)
* Non-slip hand grips for everyday hand exercises
* Reviews: 4.6 out of 5 stars / 602 customer reviews
Shiping is free w/ Prime