on apple site they demand $99/y for it - or did you mean some other source? didnt find anything directly in the ios-appstore excepting some helpers and how-tos
but perhaps my blindness asks its tribute and someone can point me (and prolly some others) in a good direction
Haha good luck programming on iOS
xcode is only available for Mac OS X - 10.6.8 and up - if you're running 10.6.8 or newer there will be an App Store for Mac on your computer through which you can download xcode for free.
$99 a year is for the developer program, which allows you to do things like download betas of new versions, and may be necessary to acquire profiles that allow you to install software on devices. Only, I'm too lazy to look up whether you do need the dev account for that