If you are looking at more academic journals, join EMRA/ACEP and SAEM. AAEM is more of a political action committee who's main interest is in EMTALA laws, corporate Emergency Medicine, and malpractice, whereas EMRA/ACEP/SAEM are more into the academic parts of EM. Good thing about AAEM as EMRaiden said is its either free or very cheap. I am not a member of SAEM but likely will be.
Q, DO