Amazon offers White Castle Gift Card for with free shipping.

Product Description: 
A quick serve family owned restaurant chain that encompasses 12 states and a multitude of cities in these states.  The home of The Original Slider® which is made of 100% beef and steam grilled on a bed of onions. 

• The White Castle gift card can only be used to make purchases at participating White Castle restaurants.
• Redemption: Instore
• No returns and no refunds on gift cards.