I would agree about the size being small, but that is only my opinion based on my belief that starfish have feelings.
But regardless of that, I think they will survive fine if you do it. If you do it, be sure to feed them like you feed fish, because there probably won't be enough to scavenge on in a small 10 gal.
EDIT: I don't know about a blue starfish though. I hear they are one of the more difficult ones to keep. I would try some other one, like say a serpent or brittle star.
cheers,
kris