Appeaisal District Market Value

[Ebony Townsend]

I have a property under contract in Wharton Texas.  It is a Fourplex each unit containg 2 bdrm 1 bath.  Each unit rents for $600, currently all occupied, and tenants pay utilities.  There are no comps for this property whatsoever.  However, the appraisal district has it's market value and appraised value at $246k.  The question I have is if there aren't any comps how close is the appraisal district value close to the actual value of the property?  I am looking for a property with good cash flow but more importantly equity.  The fourplex is currently under contract for $130k.