Most local GameStop stores carry physical Steam cards. If they are out of physical stock, employees can often print a Steam Wallet code directly onto your receipt after purchase.
(Variable amounts up to $500 may be available in some locations). Payment Method Restrictions can you buy steam gift cards at gamestop
It is important to note that GameStop has strict policies on how you can pay for these cards: Go to product viewer dialog for this item. Steam Gift Card Most local GameStop stores carry physical Steam cards