I know this is not for everyone, but amongst other cards, Samsung Pay currently has $50 Domino's eGift cards for $40. I prefer this over other sites as it directly adds to my Samsung Pay wallet and more importantly, allows me to use my PayPal balance to buy the cards!
Link is only to refer you to Samsung Pay only.
Install / Open samsung pay app
login / sign up
Click on "gift cards" at the top
Scroll down or search Dominos and buy GC