Try the Canon lens, get it from a place you can return it if you dont
like it, I tried a cheap Cokin lens it is pure junk.

I use a Raynox 0.72x w/a converter with my Powershot G5, and think
it worthwile.  But there is a lot of junk out there - in particular
on eBay.

Here is my notes on w/a converters, including links to some user
reviews:
  http://heim.ifi.uio.no/~gisle/blog/?p=6

Here is my notes on two converters I own:
  http://heim.ifi.uio.no/~gisle/photo/wa.html

Get the Lensmate 52mm converter, then one of the 52mm wide angle
converters, such as the Raynox DCR-6600Pro.

See "http://www.lensmateonline.com/newsite/A620A610.html"

and also look at the wide angle image gallery at
"http://www.lensmateonline.com/newsite/A620A610wide.html"

At least with the Raynox (and most other non-Canon lenses) you have a
threads in the front for filters.

The Raynox appeared to be the best choice, and as a bonus it's also the
cheapest.