I often wonder about these topics as it's readily available in my area. I leave it on the shelves unless it's $0.06 per round or similar. Most local stores have at least some brand in for around $0.10 per round. The cheap stuff tends to be Remington. Branching out to try different brands, I ordered 4 boxes of Federal Match from PSA and had it at my door in less than a week. I just bought 2 boxes of Winchester locally. Checking back online, just hitting a few sites, all have them had some in stock.

PSA - Federal in stock and less than $0.08 per round
Federal 22 Long Rifle 40gr Solid Champion AutoMatch Ammunition 325rds - AM22


AIM Surplus - Many different brands in stock
.22 LR

Wholesale Ammunition - Several brands in stock
Ammunition - Featured Items - Military Shooters LLC

If you don't want to search several sites, use AmmoSeek like someone mentioned. There's also slick guns:
https://www.slickguns.com/category/ammo?caliber=3

By the way, I have over 13,000 rounds currently. Sounds like a lot, but 3 of us went through more than 600 rounds Sunday. So with that rate, we have about 20 range sessions. Any friends come over and that rate doubles, so 10 range sessions. Not excessive by any stretch.