What kinda (bottles of paint) can you use on the walls that WON'T come off?

I am going to paint my baby nursery for my baby and I need tons of different colors of paint for painting zoo animals on the walls.it must be something that wont easily come off and it must come in bottles like u would see in an art class (dont need large volumes of each color) please try to suggest something that I can use that isn't rediculously exspensive and can be purchased somewhere like Walmart ben Franklin or Michael's cuz I have no idea which kind to get so if ur an artist maybe u can answer my question.thanks :)