Take the above advice. This isn't Kijiji/Craigslist where you can bs. These guys know their stuff.
I've been in your situation, put up a price for an item and get told that your off on value. Adjust the price and live another day. Don't take it to heart.
You're a recent member. Keep reading old posts, realize your not the first to get called out, and you won't be the last.
Besides, I believe the drama started when the other guy stood up for you. His words kind of got the hackles up.
There are great folks on here with a wealth of knowledge, and then there are guys like me who don't know chit.