When I've had VFT's go to seed, they just did it on their own and it wasn't much effort to collect them or mail them. Plus a lot of people get VFT seeds and give them away or sometimes offer them for sale for a modest price, say maybe $3-4 for 20 seeds (just off the top of my head). But as you say, if I made an effort to cross pollinate two interesting VFT's and made the effort to avoid selfing them, perhaps people might pay $5 for say 10 seeds (with shipping included) and take a chance on something new. Also it depends if the amount of money is important to your budget. All very subjective. And then there's the love and adulation you will get from giving away stuff (if you can afford to). Priceless