Hey starmask - regarding the question you asked me. You are correct, if people place offers, they are to be held to everything, not what they want at the end.
As for your fear of retaliatory feedback, when discussing it with Shrike, he said that retaliatory feedback is not tolerated, so it should not be an issue.
Of course, negative feedback should hopefully be the last resort. I'm sure that most good CAGs would be able to work things out with you if they did indeed place offers on your items.
If you want to give me any more info on who this may be or any more about the situation, feel free.
If you have any big issues though, I would recommend the mods.