I have both Sigma and Topeak computers and recommend both of them. My favorite is the Topeak Panoram because you get all the basic info on one screen and it's easy to read (I have poor eyesight.) The wireless version of the Panoram (which I don't have) is $45 at http://www.performancebike.com/shop/...tegory_ID=4110 and the wireless Sigma is $30 http://www.performancebike.com/shop/...tegory_ID=4110
The nice thing about the Sigma's are you can attach them to your stem rather than just your handlebars.