The dominant strategy is to bid your true value—exactly what the object is worth to you. Figure out what an appropriate market value or what a price you as the buyer is willing to pay. Gain help from a Real Estate Agent, an Agent can use their expertise to do a Comparable Market Analysis. In turn, the buyer and the Agent can make a determination within reason of other similar properties based on location and other reasonable factors. The internet makes it easier than in the past decades. Each county appraiser makes an assessment each year.