Adapting template

Hi,

I’d like to create a Wordpress site similar to this design Fibonacci Layout ( see here for full article).

A colleague with Wordpress experience advised me not to bother to create a template from scratch but to rather use an existing template from Themeforest and adapt/change it the layout I want.

Can someone suggest a template here that I can adapt/change?

One more thing though the template in question must have online shopping capabilities, or means to easily add it.

Thanks

Johannes

As an alternative how much must I budget to have the Fibonacci template built from scratch?