How can I best get hold of some basic energies? I've just started playing, I bought a starter deck and while it has some Dark and Psychic energy in I would like the other colours too. Does energy come in booster packs? I haven't found any so far. Can I buy a box of all different energies?

My local games shop has just started running Pokemon events and I want to get in on it. So the local shop doesn't sell singles or things like that yet.

Thanks in advance!!