A much cheaper solution (as in free) is to install a Dvorak Lefty keyboard layout. This keyboard layout places the keys in a much more logical arrangement for left-handed typing. I have created an OS X version of this layout, which you can download from this post on my blog. [3.2KB macosxhints mirror]
Uncompress the file, then install it by placing it in /Library -> Keyboard Layouts, and then logging out and logging in again. You can add it to your input menu list through the International System Preferences panel, under the Input Menu tab. The list is alphabetical, and the name of the layout is DVORAK Lefty, right next to the standard DVORAK labels.
Now, the hard part: learning where all of the keys are. You can write on most keyboards (I'll only vouch for PowerBooks/MacBook Pros, not MacBooks, etc.) with a Sharpie, and you can get the letters off with rubbing alcohol. That's if you're cheap and don't mind making your keyboard look hackish. If you want, you can find key pullers and actually rearrange the keys, or you can find any number of stickers on the internet for a more professional look.

