[guineapig]

Long story short: poison really isn't worth your time in classic. You have to trust me on this one. But if you are still gung ho about it this trivial list should help get you started:

regalis poison (16) poison vial suspension, urticating hairs (dune tarantulas), froglok poison gland

asp poison (24) poison vial suspension, 2 asp poison sacs (cistern asps)

basilisk poison (32) lined poison vial suspension, 2 basilisk eyestalks

crystal eritus (40) lined posion vial suspension, 2 crystalized marrows (ice boned skeletons)

cycian butil (48) lined poison vial suspension, 2 cyclamine corms, snake venom sac

putrid desil/bane (56) lined poison vial suspension, 2 putrid bies (fire drakes)

sweet lathyris (60) lined poison vial suspension, 2 ichors (large wooly spiders), giant wasp venom sac

lixt wing dust (76) lined poison vial suspension, 2 embalming dust (mummies, dark bone skeletons)

festering nettle (87) lined poison vial suspension, 2 ashroots (fire imps and/or foraged in Lavastorm)

If you get this far and feel it's worth it to keep going than more power to you!

Other things of note:

You get the apply poison skill at 18 but you can't make poison till 20. Both will need to be trained at your nearest rogue guild hall.

The vendor sold stuff can be found in WK and DC (both are fairly close to druid and/or wiz ports).

Learning pottery might help save you some money.

Finally, start hoarding components at level 1. Every spider, snake, basilisk you kill can give you items you will need once you start making poison. Try to level up in areas where these items will be available and check out the vendors that are nearby as practically nobody collects this stuff.

Nothing sucks worse than starting off a tradeskill only to find out that you will have to spend countless days killing green mobs for components that you have been leaving to rot for the past 20 levels.