Elance is a legitimate site. The big three for hiring freelancers are *****.com, Elance.com and freelancer.com. There are many good developers on all three sites and also some scammy ones.
For best results:
1. Setup a clear project summary. Make sure that you detail all the changes that you need.
2. For small projects, use a fixed price contract.
3. Document everything on site.
4. Do your homework when you hire. Look for freelancers who have completed lots of projects and ask good questions when they place their bid.
5. Test, test, test your work.