Make sure you need a custom barrel first. There are a lot of nice off-the-shelf barrels out there. I only "need" a custom barrel when the gun I have planned is unusual. Like a Hudson Valley fowler with a 54" barrel, or maybe a special octagon to round barrel to closely replicate an original smooth rifle, etc.
Next, don't take one person's recommendation that Maker "1" normally delivers within 3-6 months. I have waited over a year from nearly all the makers that have been mentioned. Sometimes more; a lot more. Sure, a customer may place an order when the guy is set up for something like that and doesn't have a backlog, and get a barrel in 3 months. Next time, could be 18 months. Not kidding; not complaining either.
Some makers want a 50% deposit or so to start on a barrel, and when they do, it's a good sign you may get your barrel within 6 months. If they are not asking for money, then they probably have a big backlog and know they won't be able to fill your order "soon".
The only way to "fix" this is for prices to go up 20% or so. Demand would go down and delivery times would, too. I can wait. There are a lot of fine off the shelf barrels out there to keep me busy building while waiting for a custom one to come in.