BUYERS, What Issues have you had with Sellers and Listings that Prevent you from Buying?

I believe you need to be "realistic" about how valuable your used equipment is, some of the listings I see that seem to hang out there for days are not IMO properly priced.
I also find that when I list an item and include UPS Ground (lower 48) and the PayPal fee, I don't seem to have problems selling items on Audiogon.

A fair amount of sellers also won’t provide a shipping cost until you commit to buy as they want to make sure that they pass on actual cost to consumer. However, this creates friction as the buyer wants to know what they are paying before they commit.

This has never been a problem for me as a seller. The potential buyer asks me to calculate the shipping cost to his location. This way the price is fair to both parties.
The Audiogon shipping calculator is not even close to reality.

Once we know the actual cost, it can be used as bargaining chip or passed on to the buyer if it’s a reasonable price.
   And I never charge the PayPal fee to the buyer.

That's the problem. Sellers have been burned by the A-Gon shipping calculator so they sometimes want to visit the shipping store first before quoting shipping price.

Just another example of an inefficiency in this marketplace. Supply and demand Econ 101 assumes that markets are efficient, buyers and sellers behave rationally, and that the products are near commodities....as we all know, none of these conditions are true and that prevents transactions from happening and ultimately depresses prices.  

I look for the lowest priced similar items either on sale or sold and make sure I price a few dollars less AND accept offers on listing.
Quote a fair shipping price even if you may lose a few dollars if you end up shipping coast to coast, it usually evens out over the years.
Do NOT ask buyer to pay ANY fees of any kind, this will assuredly put them off and have them looking at other ads.
Make sure some halfway decent pictures if possible.
Above all be courteous in all communications even if you privately are thinking what a jerk!
You never know , that "jerk" might be a rich one....lol.

@ebm  perhaps you don't recall when you first started out on this site?