They used to show up on e-bay all the time till the policy about gun parts was changed.
Recognize that there aren't a lot of 7-08 Rugers and so finding a take off barrel might be difficult/take a while. Most guys that buy 7-08s do so for a reasin so they seldomg end up as take offs.
That being said, I had no sooner voiced an opinion on just how rare/uncommon 7-08 #1s were when a #1 barrel for a stainless "B" in 7-08 showed up on Gun Broker. It's coming to live at my house.
I check there and Action Arms at least once a week under rifle parts - barrels on both sites.
Ross