Your use of "new" is a bit confusing. Are you looking for a barrel for the Model 1200/1300 series made by US Repeating Arms until 2006 or the new Model SXP?
If the 1200/1300, you are probably going to have to go used. Check the local gun shops.
If SXP you may be able to order one in through any Browning/Winchester dealer. I believe they are made in Turkey by Yildiz. If so a Yildiz barrel may be the same and may be less expensive. Might be worth checking out.