Hi Eccho. Welcome to Geekhack. I'm sorry about the late welcome. I haven't kept up on this section as much as I should.
I like the layout on that Keycool, good balance of size and function.
You don't need to spend absurd amounts of money on fancy exclusive keyboards. That's one of the best things about the hobby. Some of the best switches are pretty affordable, and the case, outside of durability and tone of sound, is functionally irrelevant.
That sounds like a fun project. I want to hand wire something too at some point, I don't know if/when I ever will though since I don't really need any fancy/weird ergo layout or anything.