Listen peps and sorry satan Ill delet this comment if you want, but how do you value if an item is rare or not? In my opinion it depends on how many there are in the game, cobble isnt rare cause there is cobbl everywhere, this is an item that yes, a few people have but it only a very small part of the community that has one of this, there for it is concider a rare as its not a common item. Now the price like with many other rares can not be defined as we dont know the exact ammount of rare potatoes in the game, but I can tell you I have only see a very very very small amount, so small most people dont even know it exist.
Being rare isn't enough, even if there were only 5 of a kind of an item on the server, the price of it will still be determined by the demand. Yes, it will be rare but it might not even sell for a Diamond. Take the potato as an example, people have bidded air, in other words nothing even though it is apparently very rare