$50
Having built a few medieval contraptions over the years, it’s going to be at least $100 for the wood alone (and that’s if you use 2x4s), and the blade will probably be around $50 for just the steel.
Guillotines can be a little finicky if you’re not careful during the building. It’s a decent bit of weight slamming down, it needs to be on-track and aligned with itself or you might end up lodging the blade into the frame.
They’re not even 2x4, we straight up lie about it! They’re 1.5in x 3.5in.
Not the ENTIRE US but most modern homes are built with 2x4s, so in a way, the US is kind of built with them.