PayPal Digital Gifts via eBay offers a $50 Steak 'n Shake Gift Card for $40. (The gift card will be delivered via email.) That's the lowest price we could find by $10, although we saw it for $3 less in March.
For regular Steak 'n Shake goers, this can effectively be $55 for $40. If you use their app to pay (which is pretty cool and makes paying your bill really quick and easy), you earn a $5 credit for every $50 you spend. So by the time you use up this gift card, you'll have earned another $5. Adding gift cards to your balance in the app is very simple, so it all works together nicely.