Wikibuy is available for Firefox! To install, simply go to wikibuy.com to install and create an account, or go to the Firefox Add-On page here.
Wikibuy for iOS devices has arrived! Search for ‘Wikibuy’ in the app store and get better prices on your phone right away, or visit the app on iTunes here. We haven't released an Android app just yet, but it is on our radar and we hope to in the near future.