I believe the starting point for valuing a tax or accounting business is annual revenues times a factor of 1.  That factor goes up or down depending on various factors including the profitability of the practice.  But when doing those calculations, it is assumed that the person that buys it is planning on being able to run it.  If uncle thinks it is worth a billion dollars, tell him that he can come down and get the keys anytime.  Otherwise write him a check for $150 to cover the value of the office equipment and call it even.  If he prefers picking up the keys, tell him good luck and walk down the block and open up your own tax practice in your new digs.