You see a theme on Themeforest and you would like that to be the starting point for your own new Drupal website.

I can do a fresh install of Drupal 7 and then install the Themeforest theme. I will install any demo content provided by the developer and set the theme up to look as much as possible as the demo website.

From there you can continue developing your website and adding your own content.

DEMO CONTENT
Please note that the supplied demo content can sometimes differ a bit from what you see on Themeforest. I follow the same guidelines concerning demo content as Envato uses in their Express Installation service:
https://studiosupport.envato.com/hc/en-us/articles/202950554

The supplied demo content can vary quite significantly from one theme to another. I can only work with the provided demo content. If you have issues about the amount and quality of the demo content, this is something you should speak to the theme author about.

- While I will try my best to make the website look as much as possible like the demo, it is not part of this service to manually add content to achieve this.

- Sometimes the images as seen on the demo are not supplied with the demo content. This is usually for copyright reasons. Sometimes generic placeholder images are supplied instead. Look for messages at the bottom of the theme product page saying something like "The images seen in the demo are not supplied...". It is the intention that you should replace the demo content with your own content. The supplied demo content is not intended to be your final website content.