Custom web design necessitates the actual customization of a unique and original website design. It does not mean modifying a template site such that it appears to be a custom site upon first glance. Custom web design is the only way to get full flexibility when building a website. When you start with a template you are building your website in a box. It might be a pretty box, it might have nice ribbons and decorations but 100% of the time it will come with restrictions that cause you problems somewhere in the future, if your site becomes successful enough.
The only likely exception to this rule is the person who is building a blog site in Wordpress because of the advantages wordpress offers toward optimization. Other than this single scenario, custom web design requires starting a website from scratch and then building it out in the numerous ways that it might facilitate the sales or distribution of your product, and in a way that allows for continual growth.
Further, if you are working with a web designer who has created many and varied custom web designs in the past, he will have a certain amount of your coding done before he begins working on your site. Naturally, he might be reluctant to admit this to you and more than a few web designers are willing to get paid even multiple times for the same work. However, not every web designer will charge you for code he has already written and many custom web design experts will tell you they have a nice head start on your project already, due to having built this or that site.
You can often help yourself to some of this information by being thorough enough at examining the web work your custom web design group has done in the past. Don't be shy about asking for a discount if there are very similar sites to yours in your designer's portfolio. You may only get a long winded explanation which explains why your site requires brand new code, but you might get a nice discount as well!
Custom web design is simply not that much more expensive than a template, if you are willing to search for the right custom web designer for your site. If you are searching the web to find your designer, don't type web design into Google search. Type in exactly what you want: inexpensive custom web design or perhaps even cheap custom web design if you don't mind risking being thought of as cheap! It is amazing how much closer you can get to exactly what you want by simply refining your search term more specifically!