If the board is small (10x10cm or less) it will be almost completely free, like single-digit dollars, through somewhere like JLPCB. So I’d say don’t worry too much about that, just jump in and try!

As for actually designing, it’s a little more complicated than that but not by much. I did my first pcbs with KiCAD ~5 years ago by pretty much just guessing and googling where things were. Completely feasible if you have 0 background experience.