Well first off,
do you want a babydeath? im assuming you do, and Opteka and Century make quality stuff. Opteka makes a 43mm, you can pick up a cheap ring to adapt it. I've heard Century makes a better product, but it's also more expensive. If you need to something quick and don't have monies, you can buy a cheap wide angle and flip the lens. You just screw off the little ring, and take the lens out, clean it, the put it back in upside down. It creates a fisheye effect. Hope that helps.