Hmmm. Hard brick or IFB? I rebuilt my kiln in summer of 2022 using k26 IFB, they were a little over $6 each. If you’re thinking salt or soda firing, then you’ll need hard brick, and where I am that’s more $. Where I am everything costs more, especially heavy things like bricks. It’s the state that stupid people think is an island next to Hawaii. In Pennsylvania you will find much cheaper bricks. Used or new. Pencil it all out, burners, tanks, kiln shelves. Beware of false economies, it is not generally a good idea to make your own bricks. You will learn how bricks are made, and it’s hard to put a value on that, but it won’t get you a cheaper kiln. Speaking from experience. Beware of respirable silica, not the dust in your studio, but the stuff that’s actually dangerous: ceramic fiber and fiber board. Absolutely the cheapest thing you can build a kiln from. Fast. Easy to work with. Fragile. Friable. Respirable. I’ve built my own kilns for twenty years. You can build cheaper than you can buy, but go slow, learn before you act, look at other’s kilns. You can sure as hell find cheaper brick than that. Do it!!! More on reddit.com

No. Online isn't the place to buy them unless you're buying pallets of them. Then any place will sell them for 3-4 bucks per brick.the freight isn't bad when spread out across a couple hundred bricks. More on reddit.com

I would say yes, but it depends on the block's ability to dissipate moisture. Concrete and grout retain a lot of moisture and can( does) literally explode once steam pressure builds in them faster than it can escape through the porousness of it. Try just building a fire on top of a single spare brick, make a good hot one and see how it handles it. Regardless, I have seen people use large metal bands (tractor tire rims, etc.) On the inside of a fire pit with a layer of sand, gravel, dirt, or even just air and that allows the heat to dissipate enough not to pop or crack bricks. Fire brick is an option, but an expensive and unnecessary one for most outdoor applications. Hope it helps, good luck and post pics. More on reddit.com

Look up masonry suppliers around your area.. or paver suppliers.. I bought my firebricks for about 1.50 a piece.. other place charged me 2.50 each More on reddit.com