I'm pretty sure I've mentioned this in the past - or someone else did anyways - and, unfortunately, nothing came from it - so I'm throwing it out there again.
When composing and having little to no gold on hand, you get a " you do not have sufficient gold to create this potion". Whilst this is obviously accurate, the message is, not to put too fine a point on it, as much use as an ash-tray on a motorbike.
For the player to GET that message, the game obviously knows how much gold is needed - so rather than just saying "you aint got enough gold on hand", how about actually TELLING the player how much extra gold he needs to make the potion(s)