There are all sorts of places to look at what's going on. So, this is just a guide for finding other useful information.
John Baez, a mathmatician, has a wonderful web page with all sorts of useful information about what you can do about the high cost of scientific journal articles. His suggestions include:
1. Don't publish in overpriced journals.
2. Don't do free work for overpriced journals (like refereeing and editing).
3. Put your articles on the arXiv before publishing them.
4. Only publish in journals that let you keep your articles on the arXiv.
5. Support free journals by publishing in them, refereeing for them, editing them... even starting your own!
6. Help make sure free journals and the arXiv stay free.
The most recent* information about how much math journals cost can be found at Ulf Rehmann's site.
A nice to place to look for information about which publishers let you put your articles on pre-print servers is on the Publisher copyright policies & self-archiving (SHERPA) web site. This site can be used "... to find a summary of permissions that are normally given as part of each publisher's copyright transfer agreement. " It also has some information on who owns a publishing company.
I also still really like Todd Hammon's presentation comparing the cost of journals to cars and tuition. I'll have to locate a copy of that however.
*as of the last time this page was updated or September 20, 2005