Choosing the right option for your Drupal theme
There are several ways for you to get a Drupal theme up on your site. It all depends on your skill level, time, and budget.
You can go the free (or nearly free) theme route, downloading a theme from drupal.org or from an inexpensive theme seller such as CMS Lounge. These will get a site up and running for little to no cost, but you may find yourself limited by the number of regions, quality, and features of these themes.
In the middle of the spectrum, you can purchase a more advanced Drupal theme with limited distribution, or hire someone to make modifications to a free theme. With these options, you get a fully featured Drupal theme for much less than a custom theme, or at least have a good foundation to start from while customizing it to your own needs.
Finally, you can hire a designer or themer to make a completely custom Drupal theme for your site. This will give you the most control but is the most time consuming and expensive option. There are many Drupal design and theming shops out there.
Weigh these options carefully before choosing what is right for you and your project! For further reading, this post expands on these options.