Walmart offers the Auto Drive Edgeless Microfiber Cleaning Cloth 100-Pack for $25.41. Opt for in-store pickup to dodge the $5.99 shipping fee. That's 25 cents per cloth, $14 off, and the lowest price we could find. They each measure 16" x 12".
Note: You can also get a 150-Pack for $34.04 (23 cents per cloth).
The future is uncertain for these struggling retailers, but their sales are certainly big today.