Gooberking
FGC Cannon Fodder
It almost certainly isn't cheaper. If you order all pre-made housing and PCB buttons and Wiring then maybe you would likely be over most units.I've always wanted to make my own but I am about as handy as rhinoceros. It just seems all to hard... also with importing all the parts from all over the palce and multipul shipments across the world.. it isn't that much cheaper than buying a pre-made.
Generally the wiring doesn't really require soldering since say the Brook boards typically come with headers that will screw down and clamp the wires. With stuff that is all intended to go together the difficulty shouldn't be all that high.
Doing what I did though took prototyping, and enough materials and buying equipment that eventually adds up to way, way more than just buying something. Wasn't about saving money and couldn't really be recommended as a path to that.
My first box was built into a magnetic, decorative flip top box typically sold at craft stores. Used a cheap PCB and button kit that only worked on PC. That probably only cost about $60 to make. With a basic Brook board and decent buttons maybe it could be done for around or just over 100$. And it would basically be in a barely better than cardboard box.
It was fun though, and I have something that uniquely suits my wants and needs.