I'm not quite sure, what e-ticket you would want to sell, the most common one is an electronic ticket or e-ticket is used to represent the purchase of a seat on a passenger airline, usually through a website or by telephone. e-tickets have also been introduced in road, urban or rail public transport as well as some entertainment venues and even lottery.
We suggest that you contact the airline company (if you will sell e-tickets for airline seats) or the company for which the e-tickets are being sold. Try to inquire about their requirements on becoming an authorized retailer of their e-tickets.
Hope this helps somehow. Cheers :)
Any additional input from others who are more familiar with e-ticket retailing please pitch in...Thanks!