Site build, simple structure. Commerce w/ user membership

Hi there. Looking to open and initial discussion and hear developer thoughts.

Open to Wordpress/ Joomla/ Other CMS.

Function:
UK financial learning website.
Users can log in (facebook or sign-up), buy content (videos, e-books), ask staff questions.
Very low touch initially.
Further work will be to add live learning environments, forums, interactive content.
Much of the functionality is contained in the "Academy" WP theme on Themeforest.

Design:
Logo design has been done, can be adapted to fit any theme.
Am looking to produce a similar feel to www.wallstreetprep.com with buttons for different site areas.
Problem with the "Academy" theme as mentioned above is that it doesn't convey enough professionalism. I would like to stay clear of too many high res stock photos.
Happy to create a PSD or convey further ideas over Skype if the developer is a stronger coder than designer.

Background:
Have had 4 websites built previously. See www.convexitytrading.com for my most recent project (unfinished) to see the style and quality of work I like to create.