Using Craft (Alchemy) correctly.

[Yael]

So, I know that this skill is very strong at early levels, but how does it scale into late (mid-late) levels? Also, is there more craftable material outside of the PHB?

[Pilo]

There is a lot of alchemical items in splat books.

Dongeonscape as some nice ones.

The skill itself scale quite badly with level. At level 1 it allows you to earn 6-7gp per week, at level 20, it is only around 20 gp a week. Except if you optimize it.

More seriously, 1d6 acid damage is quite good at level 1, at level 20, it is nothing.

[Hecuba]

So, I know that this skill is very strong at early levels, but how does it scale into late (mid-late) levels? Also, is there more craftable material outside of the PHB?

There are a lot of items that are available outside of the DMG. I have a fairly detailed list that I use personally. I can't post it in full (as that would probably be a bit on the sketchy side of Copyright), but pointing you at the correct books and pages is safely kosher.



DMG 128 - Standard base list
Planar Handbook 75-78 - Elemental themed items. Especially Liquid Embers (Alchemists Fire ++)
ECS 121 - Several splash weapons with different energy types
CAdv 119 - Assorted small skill bonuses. Also capsules (which I've never bothered with)
A&EG 32 - fire to weapon, alchemical sling bullets, non-combat tools and minor non-magical healing.
CSco 111 - Save and skill bonuses, non-combat tools, some combat tools targeted by DR type
Dungeonscape 30 - Trollbane, several items for dealing with environmental hazards
LM 74 - Undead themed items
LM 75 - Positoxins
FCS 96 - Alchemical Sleep gas (along others)
Frost 78 - Several, primarily for cold-based environmental hazards (though razor ice shards has combat functionality
CM 134 - Primarily non-combat tools
Underdark 67 - Primarily non-combat tools
DotU 67 - Shedden (+NA), and non-cmbat tools
T&B 72 - Healing Salve (non-magical Potion of CLW), some non-combat tools
Sand 99-101 - Shapesand. Slumbersand. Also several items dealing with heat dangers.
LoD 191 - Witchweed Stick (forces concentration check)
OA 78 - Eggshell Grenades


There are also some I've not reviewed in detail (didn't get around to it before I used an alchemy heavy character last) in these books:

FoE
Savage Species
Stormwrack
HoB
RoS
RotD
BoVD



As to how long the utility lasts, you can probably manage into the low teens if you really need to. Keep in mind that you can technically stack precision damage on the primary target of the splash weapons.

There are some things that would be significant issues (you can deal with ability damage - kinda - but not drain). Also, it would get really expensive to toss out 100 gp or so each attack.

[Spore]

You can push this a bit. Poison DC is the DC for Craft Alchemy for it. If PF source books are allowed, take Master Alchemist (http://paizo.com/pathfinderRPG/prd/advanced/advancedFeats.html#_master-alchemist) and push your Int. Make 50x times (Int 20) the amount of poison an average Alchemist could create in that amount of time.