Yeah, i was referring to buying them from the vendor. A quick search(im not in game right this minute) shows that the seeds are 15 allied seals each. One B rank hunt will get you 100 seals, so thats enough for 6 seeds even if youre just now unlocking said vendor. Depending on the soil you use the return is 18-36 plants per "hole"(shroud soil increases yield with higher grades giving more but even plain soil is still 18 plants, shroud soils are mostly mined up but can also be bought on the market board). Chocobo fruit take 2 days to grow, and if youre just doing this for the plants you dont really need to worry about cross breeds or anything like that. Just plant enough to get what you need, make sure to water them enough that they dont die, and then profit.