New Harbor via Amazon offers the Neewer 3-in-1 Clip-On Mobile Device Lens Kit, model no. 10084336, for $15.99. Coupon code "XBA3XBCE" cuts it to $11.99. Plus, Prime members receive free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $5.74.) That's $68 off list and the best price we could find. This kit includes a fisheye, wide angle, and macro lens; each can be clipped to most mobile devices.

Update: The price has dropped to $11 plus $4.99 for shipping. The above coupon further cuts it to $7.