Lens Cap Olympus

Lens Cap Olympus
Looking to buy Fish Eye Lens. Help me (Olympus)?

http://cgi.ebay.com/67M-Wide-angle-Lens-FOR-OLYMPUS-E520-E510-E420-E500-E3_W0QQitemZ110322094956QQcmdZViewItemQQptZCamera_Lenses?hash=item19afb5936c&_trksid=p3286.c0.m14&_trkparms=72% 3A1234 | 66% 3A2 | 65% 3A12 | 39% 3A1 | 240% 3A1309 | 301% 3A1 | 293% | 294% 3A50 3A1 What about something like this this.Is as a lens cap? Im fine lens I have "I can not just add this and get the look i fisheye? I want to buy a fisheye for my Olympus E-520. I have no idea which one to buy. I just want to buy a cheap first no more than $ 200 (if cheap)

Opteka HD ² Professional 0.20X Super Fisheye AF Lens for Olympus Evolt E-520 http://www.amazon.com/gp/product/B001K5WI1S?ie=UTF8&tag=digitalbestbuy-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=B001K5WI1S "

Damian the Cat Attacks the Lens Cap