Best Buy again offers the Logitech M325 Wireless Laser Mouse in Coral Fan or Purple Swirls for $8.99 with free shipping. That ties last month's mention as the lowest total price we've seen for this mouse without rebate hassles. (It's also a current price low for any color by $6.) This mouse's wireless receiver features a compact design so it can be left in your laptop's USB port. It requires one AA battery (included).
There's a less expensive way, and then there's the way that works for you. The two may not be the same.