I have a Micro$oft one that has 2 extra buttons on either side. It cost around $25 I believe. I have the 2 buttons programmed as Ctrl and Shift keys. They also act as back and forward buttons when I browse the web, and as a reload/alternate attack in Quake 3 (wait, did I say that?)
The Logitech you mentioned looks like it has a lot of extra bells* and whistles (holographic finish?) that add to its cost. If you have a lot to buy, you might want to save a bit of money and go for one that's a bit simpler. It looks like its one of those mice that is a right hand only model, personally, I find those mice annoying (almost as annoying as the little laptop mouse I once had that our cat wanted to eat).
*On second thought, a wireless mouse with a little beeper that lets you find the dang thing wouldn't be such a bad idea.