Make a small site with mandatory connection of the PaySera system

Experience with PaySera is very desirable, as there may be questions about the correct connection, including on the side of the payment system itself. The site will sell one product - an educational course on wine topics, after payment for which it is necessary to send the course itself to the buyers mail.
The logo and the minimum requirements for visual design are ready to provide.
Since over time the range of services will expand and including through the site will be sold in limited quantities of alcohol, it is important to provide for the possibility to add new products and sections to the same site over time. Timing and cost are negotiable.