Making a vial of acid, it adds 1pt of damage to Acid orb, if used as a spell foci. It's DC 15
Alchemy 9 + Crafter's Fortune spell 5 = Skill 14
That costs 3.5 gp
Alchemist Fire DC20 6.7gp if successful (not successful but didn't fail by 5) so can try again at no extra cost, succeeded 2nd time. Success.
Rolled a 1 so failed by 5, lose 6.7gp