^Excellent statement^ The only thing I can add is that more eyes on an auction item will most likely generate a much higher sale price for your item.
In a traditional auction format...you are completely correct. But another thing to consider is the benefit on BIN sales as well. More eyes seeing it means it has a better chance of selling faster. Even though the listing costs more, the faster you move inventory the better. You no longer have your money tied up in that inventory. It's the old "time is money" idea.
I think a credit card is required. That's how they ensure they get their fees. I wouldn't sell coins or anything valuable. But, my parents (who live in a smaller town) have made pretty good money on the side selling "garage sale" type items on Craig's List with little problem. Mostly selling tables, bikes, ect.
...that's exactly what you have to...unless you are a top-rated status...I know because that's what I was, when ebay and paypal killed my 6 figure ebay business. VIVA EBAY