WordPress is free and simple. That means that if you are tech savvy, have a webserver with both PHP and MySQL enabled and understand how to set the whole thing up you can have an online presence within minutes. I know how to do it as I have done it many times.
WordPress offers even a vast array of free plug-ins that provide you with literally thousands of different functions as well as themes that allow you to “dress” your website literally as you like. If you are willing to invest a few tens of pounds (or dollars/euro), you can buy a premium theme from a place like ThemeForest and enjoy a highly customizable theme. These are usually great solutions for simple personal websites or blogs; problems start when people believe in the myth of free (or very cheap) WordPress based website.
What I describe above is true if you know and understand where all these little pieces of software fit and how they interact with each other. The experience that our colleagues had with some of the premium themes is that, being very complete and full of gadgets, they tend to be complex and therefore difficult to adapt to your real needs.
Designing a theme from scratch takes skills and time; these both cost money. If what you need is a simple graphic implementation without additional functions or special data it might take a few hours (or tens of) and cost a few hundreds or thousands of pounds (or dollar/euro).
What happened to us a few times is people who think to be tech savvy, plan to save hundreds or thousands in web design and start putting together their own site; they even invest $35 or so in a premium theme then get stuck. The myth of cheap websites vanishes and the sad reality emerges; the website is nowhere near as professional and good as it should be and these clients cannot make the necessary changes to achieve an expected behaviour. So they contact a designer or agency of choice for help and would expect them to fix their mistakes for next to nothing. Here comes trouble. The designer or ageny has two choices: spend time trying to learn how the whole theme works (often it will take several hours just to find your way) and customise it to their customers’ needs or start from scratch and redesign the whole thing with a purpose-made theme that will not be as versatile but down to the point and working well.
I would like to clarify that most of the themes found on respectable websites like ThemeForest are very well designed are work very well; if you find one that is very close to your expected design and you have the necessary expertise to make the changes just go ahead and enjoy the low cost website.
Unless you can manage the whole process of installing and managing the whole WordPress installation and you are both tech savvy and design capable do not try to build your own website or you might waste time and probably need to go back to the designer for help anyway.