Choosing a good designer is a lot like picking out your next car; there are lots of options (style, cost, speed, etc.) and you should weigh all of them carefully to find the best option for you.
If price is your #1 concern, you can be frugal and opt for a low-end model. A quick Google or Craigslist search will reveal plenty of students, small-time freelancers and even crowdsourcing websites who are willing to do projects for next to nothing. But, be careful…you might find that you get what you pay for. Just like a used car dealership, some designers are heavy on salesmanship but never end up delivering on a quality product. In the long run, you might get stuck with a huge repair bill for a clunker of a car.
If money is no object and you want to make a big splash, a luxury model is your best bet. There are plenty of Mercedes- and BMW-style agencies around… you know the types: large, shiny offices downtown with a roster of big-name clients in the lobby. Sure, they have a lot of experience, but you're also paying a lot for the brand name.
I like to tell my clients that I am the Volkswagen of designers. Slightly quirky. A little trendy. Dependable and well built. Light-hearted and fun. Affordable, but not cheap. Overall, a good bargain for a quality product.