Game Agent has an awesome deal on Civilization V for Mac. It is 75% off: only $12.50 (originally $49.99). I Just bought it, such a deal I couldn't resist!
If you buy the box you will need to pay shipping, which is quite a lot to Canada. However, with the digital download there is no shipping. You can also get an 'extended download' offer that will allow you to re-download it for 2 years.
Also enjoy 20% off all the map packs/expansions for Civ V currently.
I bought the downloadable version, but am having trouble downloading it because my internet connection is rather slow. :-( It keeps finishing downloading without downloading the entire file... which is so annoying. I am upgrading my internet come September 11th, so I may just wait till then to download it.