Rage 2 BFG ammo is rare, but you can buy it from a vendor, in this BFG ammo guide you will get the exact location of the vendor to buy the ammo for this iconic Doom Gun.
BFG 9000 is an amazing weapon from Doom, this gun is pretty powerful but it has limited ammo slot. In the beginning, you can only use three shots, but it can be extended up to seven. The weapon is strong enough to destroy an Authority Sentry in one single shot. Just imagine how well it can work against bosses. But due to limited ammo, you cannot use it frequently so in this BFG Ammo guide I will tell from where you can purchase the Ammo and what will be the cost of single BFG Ammo.
You can find BFG ammo at Wellspring, the place where you will meet John Marshall and he will tell you to head to the Sewers. In between you will come across an area with neon lights, there are two shops one is a Trader and another one is a Vendor. Talk to the Ammo Vendor and see the list of things you can buy. The vendor is selling BFT ammo for $1000 each. Yes, three bullets can dry out your wallet completely. So use this weapon against bosses, because there it will be more valuable. In the below video I had shown the location of BFG 9000 along with its power against an Authority Sentry.
So now you know the location of BFG ammo and what is the cost. There are some more powerful weapons like the Hyper-Cannon, but you will get this at the very end when you are good enough to unlock a lot of projects.