In no particular order, I'd go with
http://www.bluedesignstudios.com/ http://www.dickmansdesign.com or
http://www.webinc.com all of them very good and with good reputation
but personally I'm choosing
http://www.fdsign.com , same quality as the ones above, also good reputation but way less priced, no need to think twice
Anyway, be smart and learn from those who burnt before you: don't go with unknown people, 99% of times you'll get crap, or nothing, or you'll wait for the work for months, or you'll be screwed
Also ask the designer about his work load and try to define a deadline. Tell him that you won't pay if the work is not made within the pre arranged time or something reasonable like 2-3 days after, and you'll see that you'll end with the ones mentioned above, maybe add 1 or 2, but no more than that. And unless you're 100% sure, don't pay in advance. Your work will take years to be finished
