Walmart offers the Zwipes Small Microfiber Pet Cleaning Cloth 5-Pack
in Grey/Black, model no. 779, for $7.53
. Choose in-store pickup
to avoid the $4.97 shipping fee. Outside of the price below, that's $2 off list and the lowest price we could find. These 16" x 16" cloths purportedly absorb eight times their own weight in water.
Of note, with orders of $25 or more, Amazon offers them in White/Black
for $7.53 with free shipping for Prime members.