Remove the build path of Last Whisper and Void Staff

This may seem stupid, but the best way to ensure those items remain late game items is making a nonexistant build path for them. Why?

: 2300 gold. That means you are going to tay 700 gold without until you buy it. That sounds like a high handicap to rush, right? If it had no buildpath, that means that it would be bought as last item, and maybe after selling another item.

: 2295 gold. The same than the item adove, but it also avoids supports rushing it.

What do you think about this idea?