Just to clarify, individual IEEE membership is much less expensive. Full membership in the U.S. is $181/year and includes online access to all IEEE articles, dues for other parts of the world are even lower (for whatever reasons) [1]. For students it's $32/year.
[1] https://origin.www.ieee.org/membership_services/membership/j...
I may be wrong, but I don't believe that membership provides journal access. It's not mentioned in the membership benefits and there are separate prices listed below for individual societies.
I apologize, you are right. I misinterpreted the information given on the membership benefits page (about the IEEE Member Digital Library).
Apparently membership to individual societies (add $9-$53/year, depending on the society) may give you access to several journals via IEEEXplore (IEEE Trans. Image Proc.; Audio Speech Lang. Proc., etc. for Signal Processing Society).
As I can't find a reliable source to quote (their page is a mess), I can only speak for myself. I became a student member because of the ridiculously high conference fees they charge, which are heavily reduced if you are a member and/or student (Conference pricing deserves a rant of its own. But I digress.).
[1] http://www.ieee.org/publications_standards/publications/subs...
[2] http://www.acm.org/membership/dues
[3] http://www.springer.com/librarians/price+lists?SGWID=0-40585...
[4] http://www.jstor.org/page/info/about/archives/access.jsp
[5] http://about.jstor.org/support-training/help/publisher-sales...