In the spirit of Black Friday*, I will give keys three times the value of what you are trading for them (original value, not sale value). I have many cheap games on my GoG and Steam wish lists. My Humble wish list is also an option.
My original post can be found on this page: https://www.gog.com/forum/general/gogs_general_trading_thread/page909
I have recently added the following games:
Learn Japanese to Survive Complete PAck
Hidden Object Bundle 5 in 1
Agon - The Mysterious Codex (Trilogy)
Remnants of Naezith
*offer good until the end of November