Replying to Wide Angle Lens

I own a Panasonic Pv Gs500, and i'm looking for a wide angle lens. NOT fisheye which may distort the image. I checked ebay, and there seems to be a great variety of lenses of all prices. Any idea on what to look for or should i just buy a cheap 20$ one? Thanks.

Btw, here are some that I was looking at:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=190314168015&Category=3323&_trkparms=algo%3DLVI%26its%3DI%26otn%3D2

http://cgi.ebay.com/WIDE-LENS-0-45X-for-Panasonic-HDC-DX1P-SD1-GS500_W0QQitemZ130315976684QQcmdZViewItemQQptZCamcorder_Lenses?hash=item1e576fffec&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1205%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50