I've had more success buying and bartering. Even when I make my prices ridiculously low selling seems to take time.
I also recommend meeting in public locations as often as practical. Most of the time it's just a hassle, but every once in a while you will come across somebody that you will be glad you didn't bring to your home.
If you get an email without any descriptive words that sounds like it could have been sent to anybody about anything it's most likely a spammer trying to get your email address. "do you still have this?" or any variation of the same idea is a real popular one.
Work off of a first come first serve bases when it comes to somebody handing you cash not emails and phone calls. Some people like to jurk you around for days just to end communication, change their mind, or turn into no shows. In the mean time you might have turned away a potential buyer or two by telling them you're waiting on someone else. They have already started looking for another one to buy before they get your message.
And if you're going to try the bartering thing make sure you are well educated on whatever you are trading for before you see it. There are a lot more dishonest people than honest. Almost Nobody seems to be willing to make anything close to an even trade. They all act like they are on some dumb#(%* reality show trading off junk in order to become millionaires or something.