If you must brew your own, do it on another character (a biochem - biochem gets better rates than gen since job level plays a role, and bios get 70 jobs while gens only get 50). You can always just buy the skill catalysts, and the expensive materials are mostly used in WoE - and your guild leader should supply you with those. Don't worry about supplies now, honestly.
I'd be MUCH more concerned about your skill build!
As high merchant (it doesn't matter pre-trans, ofc), you should go job 50 as high merchant. I get vend 10, Item Apprasial, and the rest in OC/DC. I didn't go job 50 as high merchant (it was years ago, when it was taking me like an hour+ per job level), and I regret it terribly.
Drop prepare potion to minimum prereq level unless you're making a potter, rather than a PVM/MVP gen. Unlike potion research, prepare potion does nothing for you outside of making potions and wasting skill points.
Use those points to get either Summon Flora (if you're going for a hell plant build, you must have level 5 flora; Also, you need flora if you want to solo bangungot), or Aid Potion (so you can throw blue potions to your homun), or max homun resurrection and spend the extra point on plant cult.
Genetic skills look fine - which skills to get from there depends on what you want to do with the character.
Unlike biochem potions, you can actually get acceptable rates making the genetic potions (ie, Special Pharmacy, Mix Cooking, Bomb Creation) without having to compromise your build, assuming you're making an Acid Bomb MVP build (see my build thread). Do consider whether you want to do this - if not, drop spec pharmacy back to the minimum level you need, leaving you more points for fun PVP/WoE skills.
