Good question.
I think the market would support something between $1.5k to $2k.
Right now one could easily spend that much on a big name barrel, chambering work, and then the suppressor and regulatory fees.
Obviously this would need to be a quality product that would stand on its own merits when compared to a separate barrel and suppressor. But providing a streamlined product with good balance, suppression, and accuracy would absolutely have a market.
I don’t see this barrel being for the high volume practice rifle. But a 6creed barrel (or 6um or whatever) that gets 2-3 hundred shots per season for the next 5-10 years would 100% be worth it to me.
The high volume practice rifle, the class rifle, the competition rifle; these would all be better served by treating the barrel like a consumable wear item.
But there are rifles that get used only during hunting seasons. These rifles would be perfect for an integrally suppressed barrel.