Top and side navigation bars

Here is our website user interface for desktop and mobile devices.

Basically, what we wanted to achieve on desktop, is to give visitors the ability to easily browse among all the purchase related pages through the right side navigation bar.

The questions now are: from the UX standards point of view, should we repeat the 'Buy' link in two places with different name (1)Buy & (2)Buy now? Should we repeat them with the same name instead? Should we omit the (2)Buy now label and force visitors to go back to top navigation bar to see the initial page? What about the mobile version instead?

Thanks.

Desktop:

Phone: