There is a cheaper DIY solution. It does require some soldering ability and it is not the most elegant of packaging but it does work and it's a hell of a lot cheaper than the official Canon solution. In summary it involves replacing the wired USB link with a wireless USB transmitter-receiver link. These links usually require a mains powered connection on the camera side which defeats the purpose of going wireless. However, the blog referenced below describes how to replace the mains power with a small 4x AA battery pack
There is a description of the technique complete with photos of the soldering connections on a blog by Living images (Ireland). Unfortunately I can't post the link on this forum as I am a Newbie and I don't have the requisite 5 posts yet. However, if anyone is interested just google the terms Living Images blog and you will find the blog. If you think the article is worth sharing you can place the link in one of your own posts. The blog in question is purely an information source - they don't actually sell any devices, kits or parts ... they simply describe how to build your own. I've built one and it works.
- Duke