Also a designer here. Personally i find logo creation one of the most fulfilling tasks in design.
Whoever you end up going with, make sure that they are actually designing a logo, and not just creating a pretty image for you based on your own personal tastes.
Make sure that they ask probing market orientated questions as part of the briefing process and be wary of any "designers" who do not.
questions that should be asked include:
who is your target market? This should be specific. what age group, what are their interests, how much do they earn, what kind of car do they drive.. etc. What makes them different from other beer consumers the more specific the better.
What is your breweries point of difference? What it is that you do differently, or how are your brewery presented differently from every one else. The essence of this should be packaged and communicated in a way that is immediately related to by your target audience identified in question one.
who are your closest competitors? Who is going to be competing most directly with you for the attention of your target market. These key players need to be identified so that the designer can insure that your logo will stand out when in direct visual competition with them, and to differentiate you from them. This info should inform colour choices, and the visual style of your logo.
If you are serious about launching into brewing as a business venture, I would advise you that it is a good idea to invest in quality design right off the batt.
Proper designers who take market variables into consideration when they put together your logo do charge more then you could spend on a logo competition site, but they will be much more direct in their visual communication, and you will find that this will pay off in the long run as you develop your marketing and branding for your brewery.