Where would be a good place to search for replacement barrels?

They pop up here on the For Sale section but you must be a member to gain access. Also in the Members Only section is a "Want To Buy" forum where we can post free ads for guns, parts, cases and just about anything else double gun related. For a $40 membership fee havi access to this area is worth becoming a member. Of course there are many other benefits as well but if you want parts or guns this is where they can be had.