Over the past 7 years using the different sites I've turned down 20 projects that I've been asked to bid on, and have only taken one when I was really in dire straits. You could probably make more on odesk than at mcdonalds, but you'll make 5-8x as much by building up a network on linkedin, and by posting your resume to craigslist once per week. I set my contracting rate on a sliding scale from $250/hour down to $125…
What do you actually do, for $250 an hour?
On the other hand tweaking a couple buttons could be extremely valuable to a business that relies on it's website to generate leads. Smart clients don't care how much stuff costs they care how much money it will make them.