If you just want to give it a try, go to your local lumber yard and buy 1x12 pine. Chop it up into 10" chunks. You'll get four from each plank, with one little 8" baby board left over. Find a good holder and break them.
If you want to practice more, then rebreakable boards are the best bang for the buck. We use
THESE. The green board is exactly average for a standard pine board, and the engineering is excellent. Ours have been broken literally thousands of times over the years. I periodically compare the green board to a pine board and I still cannot tell any difference (that's an admittedly subjective test).
My personal choice for demos is concrete pavers. I pay less than $1 for 16"x8"x2" pavers, which makes them cheaper than wood. And they're more consistent. The impact required to break wood changes based on things like humidity. I can leave concrete pavers in the abck of the truck and let them get rained on and it won't change how they break.
This is an old video. I was cleaning out the closet and had some left over pavers and broke them as a demo at a testing for low colored belts. That's why the power break is only 5 pavers.
As you can tell, I'm not a fan of the big silly dramatic build ups to breaks. I'll set it up and do something slow so students can see how the break is going to be done, then just do the break.
Fortunately, your inability to understand the value of breaking has no impact (see what I did there?) on the value of breaking.
Breaking teaches good technique. It demonstrates the ability to generate levels of power that most of us prefer not to demonstrate when sparring with people we like. It instills confidence. And it's just plain fun.
Videos of 5 year olds with wafer boards has nothing more to do with breaking than videos of George Dillman and his no touch knock out nonsense has to do with legitimate martial arts.
