Many of my friends are web designers – and I hope they don't get upset at this post. First, let me start by saying that great web design can have a significant impact on the type of clients you attract, the response rates of prospects clicking through, as well as the total revenue of your company.
If you believe a great product or great content can overcome poor design, you're mistaken. The return on investment on great designs has been proven over and over. It's absolutely worth the time and expense.
That said… great design doesn't have to cost you that much, though. Modern web content management systems such as WordPress, Drupal, Django, Joomla, Magento (for commerce), Expression Engine, etc. all have extensive theming engines. There are also many web design frameworks, like YUI Grids CSS, for sites made from scratch.
The advantage of utilizing these systems is that you can save a lot of your web and graphic designer's time. Professional web designs can cost $2,500 to $10,000 (or more depending on the portfolio and references of the agency). A lot of that time may be spent on developing the page layout and CSS.
Rather than paying for layouts and CSS, why not choose from thousands of themes already constructed and simply have your graphic artist work on the graphical design? Breaking up a great design built in Photoshop or Illustrator and applying it to an existing theme takes a fraction of the time than designing all from scratch.
An additional advantage of using this approach is that the layout can impact search engine optimization as well as usability – something that theme developers are typically cautious of before they publish and sell themes online. Since many of my readers are WordPress users, one of the sites I love for this is WooThemes. For Joomla, the RocketThemes has a fantastic selection.
One additional piece of advice, when you subscribe or purchase these themes – be sure to get the developer license. The developer license on WooThemes is about twice the cost (still only starting at $150!). This provides you with the actual Photoshop file to provide your graphic artist to design with!