Starting tomorrow until August 29th, Staples will have iTunes cards on sale for 15% off, so a $50 card works out to $42.50, as noted in their flyer:
While Costco’s periodic 20% off sales still are the best savings, 15% off is not bad. When you fund your iTunes account with these discounted cards, you end up saving on all digital purchases from Apple. That means your iCloud subscriptions, Netflix in-app subscriptions, in-app purchases, movies, Apple Music, Mac App Store, etc.
Staples says there’s a limit of five per family and there are limited quantities per store, while supplies last.