The astronomical prices of potatoes and onions have ensured that they have acquired the status of rare commodities. So much so that a Kolkata hypermart recently started a scheme offering potatoes at Rs 4.90 per kg for shopping worth Rs 1,499 and above, and onions at Rs 9.90 per kg for shopping worth Rs 2,499 and above. Since anything that's too good to be true probably is, here's the rider: buyers can only buy up to two kg of each commodity at a time.