Haven't head of any people who kept sea snakes, but from what I know about them, is that they're highly venomous, and related to cobras. I've never kept venomous creatures, but something to know, is that sea snakes can, and will exit the water in order to lay eggs (i.e. they can move on land). THey also eat smaller fish, so probably things like clownfish and damselfish would be your best best for cheap feedings, especially if you couldn't get them on something like silversides (I assume that trying to give one a pinkie mouse would have the snake looking at you like you were stupid).