Some years ago when I was between contracts as a freelance contractor, I had an agent call me about a job that sounded interesting in a location that was a little more than inconvenient. He offered me a position dead on my field of excellence, and piqued my interest...until the rate came in. He was offering between 1/3 and 1/2 of my typical daily rate, I think I practically laughed in his face. From there he resorted to pleading that I accept something close to the rate, and that I'd "be doing them a huge favour" if I could work at that rate. I think maybe he misunderstood why I work, and how "doing people a favour" who I have never met, is not exactly high on my list of motivations.
I think he also tried the, "but this is better than you receive with no contract at all" line...that went down just as badly for him.
Some people will do anything just to try and find expertise on the cheap, and if you have the skills, it is your imperitive to know what those skills are worth.