In most cases, you'll only make a minimal amount of gold from selling individual components.
The simplest scenario is buying Emerald and Aquamarine caches, pulling out the Shark's Blood and Fail respectively. Those components can be bought from the Bifrost, so they have sellback value of half of the shop price. In this case, you get 5k and 10k respectively. Considering that Emerald Caches sell for about 1k each and Aquamarine Caches sell for 3k each, it's a small profit.
The most profitable of way of selling cache components will be targeting stuff that Alchemists use in large amounts. There is at least one of those in each cache. In order to maximize profit, you'll need to bundle up those components in at least groups of 10. The larger the bundle, the more you can charge.
Most used components in each cache:
Emerald - Licorice
Aquamarine - Sea Water, Salt
Sapphire - Smooth Whetstone
Amethyst - Mineral Water, Steel Plate
Garnet - Tiger's Eye, Maggot Butter, Cinderblock
Ruby - Fish Oil, Haunted Object, Moonbeam, Sunbeam
Topaz - Beeswax Loaf, Topaz
Diamond - Bloodgrass, Unicorn Tears, Quartz
Gold - Slothbeetle's Carapace, Monotonite
Platinum - Adamantium, Phoenix's Tears
For the Diamond and Platinum caches, you'll have to take those with a grain of salt. The numbers are all pretty close together.