It hard to set prices, it depent of supply and demand. Here is what I believe is correct:
•Magic Residue: - I would say 50 gp
•Enchanted Essence: I believe 200 GP Per
Boura Pelts (resists): 1 - 3K Per, depending of demand. Even if I only pay 500gp, I do get enough.
•Changa Mushroom (luck): 500gp - 1k, so easy to pick up, so still good money for a young guy
•Delicate Scales (use best weapon skill): I doubt anyone will pay 15k-20k, more likely 5k
•Luminescent Fungi: Currently 6k Per - I don't believe any will pay that other than Sprago. They are easier to get from lumbering, so I think crafters max will pay 500gp - 1k or grap an axe
•Parasitic Plant: Currently 6k Per - I don't believe any will pay that other than Sprago. They are easier to get from lumbering, so I think crafters max will pay 500gp - 1k or grap an axe
Silver Snake Skin (spell channeling): 5 - 10K should be max as they are easy to get
•Ichor (nightsight): Can be crafted so max 5 - 10k
•Vial of Vitriol (elemental slayer): Can be crafted so max 5 - 10k
Powder of Fortification: 50k - I think it's still 50k
Plant Dyes
•Normal plants: 5k - 10k that ok I think
•Mutant & Naturalist plants: 20 - 30k, I would say more like 30 - 50k (black and white may be more)
•Mixed Pigments: 40k - 50k or more