A site's 'look and feel' in geek speak is called a Template, a Front End Overlay, a User Interface (UI) and the User Experience (UX), or in Drupal, the "Theme." You probably already know that ...
This document offers some guidelines on when you should start theming a Drupal project, just how varied Drupal themes can be, where to find 'free' themes, and steps you can take to reduce your theming costs.
When to Theme your Drupal website?
Your Drupal Theme is usually built almost last in the development process, yet your site design (normally .psd's) is usually created first. Your site's design not only drives many aspects of your site's functionality, it is also the most iterative process as while installing and building the needed modules and functions it will constantly be changing to add new elements and drop no longer desired elements.
Don't get attached to that first attempt at designing what your site's going to look like!
How much does a Drupal Theme cost?
From 'free' to thousands of dollars.
If you're willing to dig for a free theme that fits your needs, then all it will cost is your time. If you want something unique, or if your time is more valuable and you feel it should be used on your businesses, then it's best to hire a UI/UX designer.
No matter where you are on the internet:
- Jot notes, and the URL, of things / areas / elements / functions you'd like on your site.
- Keep your sales / marketing hat on and see if any of them would make your site sell better.
There's plenty of sites that have taken a 'free' theme and done minor tweaking to fit their needs, but it's always cheaper if you have concrete examples of what you're talking about.
Example of the Different Looks Achievable with Drupal
Where can I find 'Free' Themes?
Do note there is significant overlap between these:
freedrupalthemes.net was on this list until I tried some of their themes.