For users who don’t want to fork over $1.49 for the app (or who can’t due to lack of carrier billing in their region) you can now get the completely free and fully functional Instagram-client for Windows Phone 8. The app is exactly like its paid sibling but has some banner ads near the bottom—otherwise the apps are identical.
Those on Windows Phone 8 can pick up Itsdagram free here* in the Store.
*Note: This link is really, really new and fresh meaning the app may not yet appear in the Store in your region. If so, just try back again as the app needs to work its way through Microsoft's servers!