Also.. if you find a design firm that has particular projects you like you can try to find the individuals or freelancers that worked on them, and hire them individually. I'd google for "portfolio" combined with the name of the design firm, project or designer's name, and contact them directly. This way you get past all the process, procedure, professionalism and project management that come with working with a firm (and which bigger companies really need) and work with the designer directly. Most designers who aren't principals of their firms do freelance work on the side assuming they have time.