My list of seller red flags

So many rules! Overpriced is often subjective. No trades has got to be a personal preference. Some might like it. Price is firm is sort of a silly objection. You don’t like the asking price? Move on. And who says you can’t make an offer on a “firm price” listed item? Don’t talk about flaws? Maybe there are none. Gimmicky price to one could just be someone having a bit of fun. However, what dollar increments are acceptable? $20? $50? 
Basically, trust your instincts - if you get a bad feeling move on. I have bought and sold on audiogon but if I’ve ever had any reservation about a person I am considering doing business with, I just don’t. 

I disagree with all of it, if you don’t like the price, the description, trade or no trade don’t buy it.  I want the last 5 minutes back for even reading or replying to the original post.

12inch45rpm-sounds like you have done much buying and selling online. You think all the risk is on the buyer which is not true. The buyer can be just as corrupt as a seller and PayPal doesn’t help the seller. For example: I have had people try this unsuccessfully against my sales but other sellers got screwed and that’s caused by a seller shipping a perfectly good piece to the buyer and the buyer claims it’s faulty and sends back to the seller a no -working piece that the buyer previously owned. Every sale I do I mark the item somewhere or right down the serial # and if they pursue sending back the item, I tell them that I will only accept the unit that matches the serial # or the markings. Both times they tried this to me, they decided not to send it back. Another scam is the buyer claiming they never received the piece when I always pay for signature required and I know before they claim this scam that they already received it.
paypal almost always protects the buyer. 1 more thing, if I ship overseas, I make the buyer use PayPal with friends and family payment.im not risking loss of an item in customs or transferring from 1 shipper to another.
All of these things are discussed before finishing the transaction, and if you don’t want to do business with me, that’s ok, because I might not want to do business with you too

I would add another irritating detail, the seller indicating that they have the original box and packing but will only allow local pickup and refuse to ship the item.

Well, I certainly wouldn't want to deal with the OP as a buyer, too many issues, It's just a piece of audio gear.