Replying to GoPro lens swap, no fisheye?

It can be done, I googled. I am sure some of you know already and have done it and there is already a thread. I searchbarred, but couldn't find it (I believe it is due to the somewhat "new" way the searchbar works). Anyways, I am curious how its been done amongst my fellow NSers. Cheap= better. Also any other cool Gopro mods should be posted up, but most important to me is the lens swap. Looked it up on the GoPro sight, only found wide-angle (fisheye) swap- I am probably blind though and missed a GoPro manufactured one... Thanks!