
Chet Skolos |

Dragon 317 (March 2004) has the article "Using Power Components", harvesting materials for magic items and spells from dead monsters.
Dragon 349 (November 2006) has the article "Poison Making Guide" and the Complete Adventure also contains information on crafting poison.
I have double checked each of these articles and none of them offer any guide to pricing alternative poisons not listed in the table.
As you have mentioned, a good place to start is on page 557-560 of the Pathfinder Core Rulebook, in which they list most of the poisons you'll encounter, and from there you can build off those examples.
I've put in some more time trying to understand the pricing. The problem is no two poisons on that list differ by only one attribute. Except for Giant Wasp Poison and Large Scorpion Venom: a change from 1d2 Dex to 1d2 Str changes the price from 210gp to 200gp. I have not had much luck guessing at a formula for determining the cost of alternative poisons.