This post has been migrated and imported into different systems over the years, I have not had a chance to format this post manually so it may be hard to read but I have left it here as a reference.
I have worked as a web developer for over 8 years now and I have learned a lot from the time I started with clients ranging from artists/authors who needed a personal page to multinational corporations who had more complex requirements. I have also used themes for clients in addition to designing or finding someone who will make a custom design which I will then implement for my clients. What it all comes down to is usually budget. There is nothing wrong with using a theme for your personal page or business. I would suggest that you start thinking about a custom design when your business is ready to start working on branding, this means banners, signs, business cards, envelopes, paper and more. These should all be based on a corporate identity which a designer will make for your company.
Something like that will cost a lot of money and that may not always be an option for an author trying to get noticed or a startup which is tight on money. In this case it is much smarter to simply get a logo design and then find a theme that fits your business. I recently wrote an article about 99Designs where you can get 900,000+ designers to give you many different logo options and let you pick the best one for only $250.
Now, there are tons of places to find themes, some are free and some are premium. I prefer premium themes with good ratings from Themeforest, they will usually cost around $40 perhaps and there are tons of good ones. You can usually find a web developer who will install the theme on your web host and make basic configurations for around $100 or even less depending on the complexity. I own a web design firm and can take care of this for you if needed, simply contact us over at Anveto Designs (http://anvetodesigns.com).
Free themes would be the last option and you have to be careful when using these as some have been known to contain backdoors/malware that could cause your business problems in the long run. In the past I have found some really nice themes over at Freebiesbug.
I hope my post was helpful and I would love to hear your thoughts and feedback in the comments section below, thanks for reading!