Yes Afternic is free. (...but a terrible bulk upload imo, will take weeks before completed).
Godaddy Auctions. Commision 10%. Paypal payment.
Godaddy Premium listing. Commision 30% (more exposure than 'Auctions'). Payment only by check.
Most of my domains are parked with Sedo. 10-15% commision with a minimum $60. Paypal/bank payment.
There are also brokers like Toby Clements TobyClements.com Daily Domain Newsletter (commision 15% with a minimum of $250, may be lower on $xxx domains). He's not accepting all domains but he has a subscribers list of 16k with an almost daily newsletter.
Mediaoptions ( MediaOptions.com ) is another broker but I haven't used them.
As far as i know, listings are always free.
I have sold names through Godaddy Auctions/Premium and Sedo too but only after having contacting endusers myself. I also have my second domain with Toby at the moment.