Refill your EXISTING Lexmark C720 toner cartridges for a fraction of the cost of buying new ones. Don t throw away your empties, they are worth money! Uni-Kit now offers a refill solution for the Lexmark C720 cartridges. Uni-Kit is a USA trusted brand of high quality toner for toner refills. The Lexmark C720 cartridges cost over $100 for the black and over $150 for each color (Cyan, Yellow, Magenta) if bought in office supply stores.