for $50-55, you will membership to ACEP, state ACEP, and EMRA. combined you will get 3 newsletters a month, minimum, in addition to all the EMRA benefits, ie, 30 top problems, pharm guide, survival guide for med students... these are great resources for med students. EMRA has many interesting articles for med students and residents.
I would also definitely join AAEM, its free, you'll get a monthly newsletter detailing many of the business and legal aspects of medicine and it will be handy at the 25 or so 100% AAEM resident participation programs. Definitely join if you are itnerested in one of the programs that fully support AAEM. It will help u in the interview process.