If you want new, only Remington makes them currently (both pump and bolt).

There are some used ones out there from Remington and Ruger.

These guys are right though, it's probably cheapest to buy a barrel and have it put on one of the '06 based rifles (06, 270, 280, etc). You could probably get a barrel for about $100. gunbroker.com usually will have a couple listed as well.