This doesn't specifically answer your question, but a lot of people steer clear of "the big sites" like eLance or oDesk because they're worried about getting low-quality code back or having other issues with the deliverables.

If the kind of work that you need done is fairly vanilla web development (ie not scientific computing, super high performance stuff, specific algorithms, etc) I've found that you can actually get high-quality code back from the freelancers on those sites for very cheap.

The important thing is to be very specific with them so there's as little ambiguity as possible. You'll need to write detailed product and technical specs yourself, as well as create mockups of what the pages should look like. These are the components that require the most design and careful thinking.

Once you've fleshed all of that out, it's easy to hand off to someone cheap and and have them crank through it quickly. They'll usually appreciate that their project is so well defined.

So while there are definitely some horror stories that come from the "big" freelancing sites, they can definitely be a great way to hire freelance resources, if you know what you need to have built very specifically.