Hello, my name is Ayrat. As an experienced webdeveloper, I will easily build website for your needs.
I use 'Sellfileeasy' library to sell files, it is severly modified by me for Wordpress usage, so this part of your project won't be an issue.
I will provide you with clean HTML5,CSS3(LESS),JS and PHP code, as well as neat and effective design solutions. Of course, the website will work properly on mobile devices and will be adapted for SEO promotion.