Assume that Griffin Inc. purchases a customer list for $$400,000.$ Legal costs to complete the transaction cost $$10,000$ and the list is assumed to have a useful life of $10$ years. At the beginning of year three, Griffin Inc. discovers that there is currently an active market for customer lists, and it is expected that at the end of $10$ years the list would be worth $$80,000.$ 

What is the value assigned to amortization expense at the end of year three?