Finding designer is like looking for a new family doctor! It's tough! First you have to find several designers, then interview them and then you have to give them 40% of the project upfront...non refundable.
With 99designs all that stress is eliminated. You are showered with great designs, from great designers. If you aren't happy with the designs then you can ask for your money back; but I highly doubt you'll need to! Try it once and I'm sure you'll be back.