tassadarforaiur you can have multiple layouts without paying anything extra, as long as you are fine splitting the right shift key 1U on the left barrel and caps lock style shift key on the right barrel. Most people preferring the HHKB style layout want those keys the other way around, so they would then need to buy the extra parts to go between split right shift of any layout and regular shift key.
If you want to go split right shift, you'd need a split right shift top inner assembly, split right shift PCB, split right shift inside foam, and a few extra keys: Backspace (| \ sized key), caps lock style Shift Key, 1U key with "Fn" legend for the function key, ctrl/caps lock switched legend keys, a 1U | \ key, and maybe another one I forgot about?
If you don't want to have to reassemble each keyboard every time you switch layouts, you can also order just an extra fully assembled inner assembly.