Whenever I had listed coins on ebay, I usually just listed them at a very low starting price ( 1 cent or .99 ) and let the bidders decide what the value should be. I decided to set the price at the lowest I would take for the coin. I am not seeing that much of a difference in the number sold or the price realized when compared to the cheap auctions I ran.
This works fine until the day that the listing closes at a price that is significantly less than the value or, perhaps even below what you paid for it.
If I were selling on E-Bay, I would do the same thing. I would set a minimum (within reason). Otherwise, I would think that you leave yourself open to take a hit on fees, shipping, etc. Also, other times I have just made an "opening" bid just to see if there is any other interest in the coin and sometimes there is no other competition. I don't mean that I place a cutthroat bid trying to steal the coin, I just bid a price that would be a bargain to me. If I get outbid then I bump it up to the max I'm willing to pay. But, sometimes, there just seems to be no other interest and I get the coin at my bargain price. I don't know if it is the lack of interest in the particular coin, or maybe just the timing of the listing and I just happen to hit a couple day span where nobody seen it. I don't want it to sound like I'm trying to take advantage of anyone, but there have been too many times where the coin arrives at less than what the listing described, so I start at my bargain price.
Here is a good example of you just stated about wrong timing or nobody seeing it. 1 cent plus $1.00 shipping from another site. I sold it on ebay for over $20.
I tend to start auctions at 99 cents just because I don't feel like I'm turning much of a profit after I've paid seller's fees and whatnot. Haven't sold any coins on the Bay yet though.....
The day the auction ends can affect the final bidding price in a 99c auction but as long as you're covering yourself by setting the floor price, you should be fine.
I did ok with the ones I listed that ended last weekend. Was hoping for more sales but was competeing with olympic hockey