How do you determine value of real estate in Michigan when nothing has been sold recently?

We are going to have to distribute ets of a will upon death. There are no comparable sales in this area of Michigan recently. There could literally be no buyers at any price, at this time. One beneficiary will probably want money now, the other three can possibly wait to see if the market ever turns around. How do we determine a value for the one beneficiary that will want his money now?