The Axis/Edge uses the sane barrel nut system the older Savages use. You have to register, but lots of info here:
http://www.savageshooters.com/SavageForum/ They even have a forum just for Axis/Edge questions. I think you mean different barrel as opposed to an extra barrel?
Barrels are available from Shaw, Mcgowen, Shilen, Rock Creek, Brux, Pac-Nor and possibly more. Price of barrels varies depending on manufacturers and vendors. Easy to swap barrels, but the case head needs to be the same for easy swaps.