There are several inventory system guides that you can use and I can give you a link to them if you want.
*selectable_if (metal_series_mouse = false) and (cash >= 800) #Purchase Metal Series Mouse
You have the right idea there. Though if you want the choice to completely vanish you’ll be using *if.
I believe this is what you’re looking for in a Inventory/Shop system
If that doesn’t answer your question let me know.