There are now so many places to list domains for sale. Sedo and Afternic lead the pack with places like Go Daddy and their premium listings option gaining in popularity. You also have places like CAX.com or Bido.com as smaller alternative places to list your names. A lot of domainers have their own sales site along with listing names on forums like DNF or Namepros.
It makes sense to list as many places as possible to maximize visibility and gain more exposure. You do need to keep track of all of this. Not keeping track of where you have your names can cost you money.
Here is a real life example of not keeping track of listing prices, costing the domain owner money.
Another domainer and I are having a conversation about him getting an offer in his email. The typical "Is *****.com for sale and if so how much ?" He says he is looking for offers over $1000. The prospective buyer comes back and says, "How about $1500 ?" My friend gets back with $2500 counter offer.
He does not hear from the potential buyer for a few days, and then gets an email from Go Daddy congratulations your premium listings domain has sold. The buyer emails him and says "Oh I was looking to see if the plural was available to go with the singular version that you own, and I searched Go Daddy and saw your name for sale for $800. I just purchased it there. Thanks for a great transaction."
So now instead of getting a min of $1500 along with using Escrow.com and the buyer paying, he gets $800 – the 30 % commission Go Daddy makes. Netting $560 vs $1500+ is not a good feeling. He said that he completely forgot about the Go Daddy premium listing.
So make sure when you compile your list of the domains you are selling, that you list all the places and prices where you have them listed. You need to be organized and have quick access to this data so that it does not cost you money.