Generally, yes, appraisals are required for all real property disposal transactions, except when—
    
    
        
        (a) 
         An appraisal will serve no useful purpose (e.g., legislation authorizes conveyance without monetary consideration or at a fixed price). This exception does not apply to negotiated sales to public agencies intending to use the property for a public purpose not covered by any of the special disposal provisions in subpart C of this part; or
     
    
        
        (b) 
         The estimated fair market value of property to be offered on a competitive sale basis does not exceed $300,000.