Good idea, but it would require a registration fee to pay for all of the legal stuff. It would be tough to start, but once it became established, it would be the only way to buy and sell Extra Premium tobacco.
You'd have to start an Association of some sort and outline in infinite detail what "Fair Trade Tobacco" is. This definition would become the standard all tobacco must meet to be recognized as "Fair Trade Tobacco". There would be a copyrighted logo that would identify (at a glance) the product bearing that logo adheres to the standards set forth by the association. Anyone wishing to use the logo would have to be a member. All members would have to agree to maintain the standards set forth by the association to be accepted into the association. All members would have to agree to random, unannounced on-site inspections of their facilities, fields, and accounting for any related activity. Member's product would have to be tested occasionally to assure the association's standards are being maintained.
I'd guess you're looking at about $100,000 to $200,000 start-up cost. Membership fee's would be recurring annually, so that would help.
The alternative would be to start an association and bully all the competition to join for $5000 just for the rights to display the logo. That would only take about $25,000 in marketing to establish the facade of a legitimate organization just by advertizing. Once the market is saturated with the "standards", the public would know not to buy from anyone who didn't display the logo...the same way the Better Business Bureau operates.