Buy.com has this Microsoft Wireless Notebook Optical Mouse 3000 on sale right now for only $13.95 shipped, down from $24.95! If you’d rather something a little less pink, there are a a bunch of others on sale for only $14.95 shipped. (Search “microsoft wireless optical mouse” if you’re not getting a large search list through the second link)
I am a huge wireless mouse fan because when I have one of my kids on my lap and the other hanging on my back, I can still use my knee to get some work done!