I've just begun Scars of freedom in hard mode, with wounds and Iron man, after the two first fights, when we get to the general map, we have to buy some body parts at the morgue.
And in the shop interface the "cash" items has disappeared, it's still in the inventory but does not displays in the shop interface.

Any ideas of what I should do?

You are aware that you don't buy with gold but with ether at the morgue?