Reconsider Post them for at least what the NPC vendors pay... 5,000 for uncommon, 10,000 for rare for level 50's. That should be your floor.
People "sweep the floors"-- they set up stacks of wentworths' bids for all uncommon's at something low, like 100-1000. Once they have full stack, they sell them to an NPC vendor when you get full stacks. A lowbie can make a few million a day with minimal effort. At extremely high levels (or when competing bidders drive up the value) you can find your time better spent elsewhere.
You're still helping the lowbie... in a way... but not the way you intend.
Now, that price won't stop the person that wants to monopolize that recipe (buy everything at 10,000, re-list them at 100,0000) but it does mean that they don't have a win-win (they won't be able to sell excess to the NPC's for profit), and at the rate these things drop, if you recover the stock that's normally lost to floor-sweeping, it takes a LOT more investment to grab everything and maintain the monopoly.
Same goes for the people that try to "help" with giving away salvage cheap . Odds are that you're actually helping the monopolizer with your low sales. Many resource-monopolizers have bids out for the same low stock that they're then bumping up to ridiculous levels, so by offering your stuff TOO low, you're just giving them more stuff to sell at extremely high profit margins.
If you want to help drive down costs, offer your stuff at maybe 2/3 that going price. That's most likely too high for the monopolizer's bids to replenish their stock, so your salvage is more likely to go to someone NEEDING a bit of a bargain, and if enough people do it, that becomes the new dominant rate, leaving the monopolizer with only two choices: buy up ever-more-expensive salvage to sell at ever-smaller margins or pull their stock and re-list it at the lower going price.