The couple I've been checking on are in the $150-$250 range unless I decide to just cheap out and get a whole rifle kit for $400, which would either be steel or nitrided.
This triggered me a little - I've bought hundreds of $150-250 AR barrels in my life, but man, it REALLY pisses me off to think about how $150-250 just doesn't buy the same barrels it used to buy just a few short years ago. Hell, I'm not sure you can still get a cheap Criterion for $250, let alone chambered in 300blk. But that's about the quality level I'd prefer. I've had too many Faxon barrels which just don't shoot (especially their gunner profile - which you really can't do with a pistol length gas anyway), so I don't point guys to their door, same with Odin. I haven't been knocked off of my feet by Ballistic Advantage barrels, but for their price, I don't recall ever being disappointed in how they shoot. But at that price and wanting accuracy, I'm REALLY not looking for any barrel with fluting or nitriding, nothing which increases cost in any way, and I want all of the money to be in the bore. When Shilens and Kriegers went over $400, I used a LOT of Black Hole Weaponry/True Sporting Arms barrels, but they're also out of the $250 cap - I bought a dozen Tactical Ordnance barrels (almost all have been their EV-5 poly-rifled barrels, only a few of their inexpensive, traditional cut "Pro" barrels, the EV5's DO shoot notably better and clean easier (and should last longer than conventional cut rifling), but Pro's have been sub-moa barrels for sub-$200 also). PSA's standard barrels tend to be fine, and some days, I can convince myself to take a risk on a $100 barrel, but I think it's easy to guarantee better performance with a $250+ price tag (again, not including any barrels which are increased in cost due to fluting, carbon fiber, cerakote, nitriding, etc).
In general, I do tell folks to only buy kits if it's the cheapest way into the cheapest rifle they could tolerate. It DOES happen that a guy can pin a cheap upper onto a cheap lower and end up cheaper than a complete rifle - but really only for the cheapest of cheap carbines. An option there, naturally, is to buy the cheap kit, sell the barrel and FCG, and upgrade those components. A guy can put together a REALLY cheap, REALLY small shooting AR by doing so - I've rebuilt a lot of kit rifles with better barrels, better triggers, and free-floating handguards to produce sub-MOA rifles for under $1000. That's easier to do these days since more kits are already free floating, but a little hard to swallow the fact that instead of $300 for the kit, $250 for the barrel, $180 for the trigger, and $250 for a float tube, now we don't have to buy the new handguard, but that $250 for the tube got cut in thirds and stuck into the other components because of Bidenomics... Considering a sometimes-suppressed doublestamp 300blk, I'd look long and hard at an adjustable gas block. Don't be afraid to drill a hole or mill a clearance pocket in your handguard to allow access to your adjustment screw. I use JP low-profile detent adjustable gas blocks under handguards on several of my doublestamp uppers, with the corresponding allen key stored in the stock. I prefer to nest the can on my doublestamps to give me as much room on the handguard as I can get.
Might find some good memorial day sales coming up, and if you're REALLY committed to waiting for deals, Black Friday will almost always see some good prices on barrels.