If you just need design (little "d"), it would be hard to recommend anything other than 99designs.com, since you can get dozens of people to do the design work you need on spec, at effectively no cost to you, then pick the best (or none at all).

If you need Design (big "D"), then you get what you pay for, and you should be going with established, known quantities like an identity/brand specialized design agency. They do cost a lot of money, but that's because Design (big "d") is very hard.

The difference is that Design (big "D") is about strategy and communication, whereas design (little "d") is about drawing and coloring. Sometimes you need one, sometimes you need the other, and sometimes you need both.