You can try McGowen barrels, their lead time is about 10 weeks and they can also rebarrel it for you.
Lilja takes about 13 weeks.
Shilen is running about 12-13 weeks.
Just bought a Douglas about 2 months ago, it was delivered in 5 weeks. I threaded and chambered it, it's sitting on the bench right next to me.
Green Mountain Barrels sells blanks, taking about 3 weeks last time I ordered one.
You can buy Bartlein barrels from Grizzly.com.
ER Shaw makes barrels, but I can't tell you what their lead time is since I don't use Shaw barrels.
You will have to find a smith to rebarrel it once you have the blank in hand.