Since by this level of crafting we are all pretty experienced with gathering reagents and the basics of crafting they threw a little extra challenge at us. trust me when i say it is M.u.c.h. easier to accomplish now than it was before Khrysalis and Aquila were released.The only way to get it at the point you are at is to gather as a rare harvest from agave leaves or battle bosses like cronus and gladiator for a chance at a drop. If I were you, I would ask my high level friends where they think is the best place to get agave leaf. I prefer not to announce it here, but in game I would take you right to it. Good luck, I know you can do it.
I tried the same thing back then I gathered a lot of agave leaves from the place it told me and was going to transmute it but it said I had to be transcendent so I went and just farmed as much as possible.