If you have domestic resources work on it, a basic site can easily cost $3,000-5,000. If your morals permit you to use outsourced talent, you might pay $500-1,500 for the same product. With the many freelance websites the global talent pool is easily accessed. However, you generally need someone tech-savvy to project manage foreign resources, as communication barriers can be significant, and if there's any sort of commerce involved I'd seriously question taking that approach.
The main thing is to know what you want the site to do and have a good sense of how it should look and feel... even hand sketches help.
Try to have your web talent use common open content management systems, because you might need updates in 6 months or 2 years and your original programmers probably will not be around. Using something like Drupal, Joomla, or WordPress is going to make it a lot easier to find talented people who can update or add to it, and also make it much easier to add functionality quickly and cheaply because much of what you may think of has probably already been created as a module that can be plugged in, so you're not paying people to reinvent the wheel again and again.