Retailers like Walgreens often stock MyVanilla cards in their prepaid card sections.
You can sign up directly to receive a personalized card in the mail. There are typically no purchase fees when signing up this way, though ID verification is required.
Regional chains such as H-E-B and Dollar General frequently carry them. Buying Online
You can buy a MyVanilla Personalizable Card by signing up online at the official MyVanilla website or by purchasing a temporary "Starter Card" at a variety of retail locations. Where to Buy In-Person (Starter Cards)