If our bid seems high on a particular project, and you don't understand why, then consider the old adage: "You get what you pay for." This does not mean that we are better than the next bidder; rather, it means that you should be wary of low bidders if you are looking for quality writing. Anyone can create a Profile on Elance, claiming anything whatsoever as experience.
Many writers live in non-US economies, and as such, can bid lower than US writers. This is great for competition, and writers who don't like it should consider relocating to those economies. However, a disparity arises when "writers" masquerade as native-English speakers, and their bid is backed by someone with a US address who farms the work to writers abroad. This is deception, pure and simple.
You will find that many serious Elance Buyers request "native-English" speakers. This is because (good) writers from the US or Great Britain--in general--can write better than any writer from Klakastan (or anywhere in the world), even if that Klakastani writer has an advanced degree in English--or any subject, or any degree, or any number of years of writing experience. This is an artifact of native languages. There are exceptions, as any translator of Hermann Hesse will argue, but the fact remains: English writers are the best writers of English.