Amazon.com (not Amazon Canada) has the 4-disc Blu-ray 3D/Blu-ray/DVD + Digital Copy + Digital Music Download combo of The Avengers on sale for just $19.99. For comparison on Amazon.ca the 4-disc combo set is going for $37.99. This is the ultimate set for any fans of the movie. It comes with the 3D and regular Blu-ray version of the movie + a DVD and digital copy as well as a download of the complete movie soundtrack.

You will be charged additional shipping that will cover import taxes & duties. Those should work out to just under $8.