I have been researching fire bricks for the last 2 months because I'm going to build a masonry heater and one needs a lot of fire brick for a masonry heater. I've spoken to several masons and I've learned all fire bricks aren't created equal. There are low, medium, high duty, and super duty fire brick. And usually the price goes up with the duty status. The duty status mostly corresponds to the ratio of silica (sand) and alumina (metal). The higher the alumina content the higher the duty status, and price.
However high/super duty fire bricks aren't as good at temperature cycling - which means going from hot to cold, but they still might work. They like to just stay hot all of the time. So medium duty fire bricks are good choices for things like wood stoves which cycle hot and cold. And low duty bricks will work but may start pitting sooner.
The two brands that the masons who build masonry heaters like the most seem to be Alsey and Whitacre Greer. Masonry heater cores reach temperatures up to 1800 F so the masons know who makes the best bricks. This high temperature in the core is one reason why masonry heater's really outperform wood stoves. Yet we in North America think wood stoves are where it is at - go figure. We just don't know any better, but Europeans do (as usual). Cost? I'm building a masonry heater for less than $1500. Anyways, the #1 fire brick is the Alsey Smithfield fire brick - not too expensive and a great brick.
I researched how to get these bricks. They can be had for about $1.20 - 1.60 each directly from the factory - you just have to buy them through a distributer then go pick them up at the factory - or have someone pick them up for you. Alsey is in Illinois below Chicago, closer to Springfield. Alsey plant's phone # is (217) 742-5501. Or check out Alsey Refractories.com
I live out west so I couldn't get this brand but I see you are in the midwest so you're not too far away. If you buy a half pallet the price per brick goes down further. I ended up getting a pallet of super duty bricks (Government surplus) for about $1 a brick so I'm going to build a masonry heater out of these and pay close attention to fracturing - it is still kind of unknown how super duty bricks will perform in masonry heaters. Hope this info helps.
The reason why I can get a masonry heater so cheap? I have learned how to build one - not that difficult, I got the fire brick cheaply for the core, I got the outer bricks for free. My other costs are the door ($400), special mortar, some hardware, and piping. I'm building a smaller heater, however. But it will still kick any wood stove's butt!
