If you can't find flash cards, our son's DT used the bathtub letters.
She would hold them up and have him repeat the sound the letter makes, not necessarily the letter name. Our son was working on articulation.
He's 3 now. His current favorite toy is a Starwars electronic game that looks like an R2D2 computer. We found it at Target for about 20$ at Christmas. It has him hunt for letters on the keyboard. It counts asteroids. It has him hunt for shapes. He plays with it everytime we get in the car.