I can feel very little sympathy for the OP (certainly without them giving more details as to why I should), harsh as it may sound.
If you know the value of something, then why sell it for less?
If you don’t know the value of what you’re selling try doing a little research before someone more savvy haggles you out of some money….
If genuine miss-representation has taken place and you thought you were being “Philanthropic” but were actually being mugged then tell the STW Admin…
You may or may not get sympathy from the STW membership, but you will see no action from them…
If it’s simply a case of Kids flipping on parts/bikes via ebay/SDH/Bike radar where prices are normally over-inflated; then it has always happened, and always will, they’re smarter than you, get over it…