I've seen this exact attachment in ebay. However, the variants I saw came with a clamp-like structure that holds onto the sides of the phone (just like a monopod attachment). The one in the photo you posted could either be specially designed for the L1020 case shown... or it was just made to stand on the phone to make it look like it's attached.
BTW, about modding the camera grip (as in post #1): although this may seem convenient, note that if one will be attaching a lens that would fit the entire diameter of the hole of the camera grip, the axis of the lens attachment will not be aligned with the axis of the lens of the camera itself. This may lead to unwanted distortions and chromatic aberration. My suggestion would be getting one of those lenses that can be attached using a grip that holds onto the sides of the phone like a clamp of a monopod attachment - this way, the attachment lens can be aligned properly with the main camera lens (as in post #129).