Why are ridiculously low salaries offered nowadays to well educated candidates?

Most of the recent college grads cannot find job and those who do get job offers, discover that the rate being offered is ridiculously low. For example, I graduated with bachelor of science in mathematics back in 2008. For many many months there was no job that I could find. Then I gave up hunting for job and instead decided to pursue master's in math. When I heard news by the phony Obama circle that "job market is picking up", I started to apply for job. Then I finally got a full time job offer as "energy analyst". I then discovered I am being offered 13.50 an hour only. That is ridiculously low job offer for someone having bachelors in math, computer science, engineering or physics. People make that without any degree working as cashier in store. I questioned why 13.50 an hour only and the recruiter said in an apologetic tone, "this is all we can offer. times are tough". After some more conversation I discovered that it is a "temp" job. Then after some more conversation I discovered that there are no benefits being offered. Then after some more conversation I also discovered that, "training will not be paid. first 4 weeks is training". So he is saying that for the first 160 hours I work free because training is not paid. And then its also a temp job. I thought after 160 free hours, he will just say "its temp job so its over now" and take a lot of work. I refused the offer.