Once a person with the potion skill gains a potion, they can ICly learn to recreate it unless the creator does something to obscure the ingredients. They have to obtain it from the original source first. (So a meager healing potion would be like Vita on the Rewards page, and only a person who purchased Vita at least once could make it.)

That's the current method, but I totally see where you're coming from on the basic potions, so we will come up with like a mega-basics recipe book from the alchemy classes at the school or something (ngl mod derped on this thought so we're gonna brainstorm and flesh it out and get back to you on that) and introduce it later in game. For now, please go with the above statement.