1) Assign too high a value to 2) Overestimate 3) Set too high a price on 4) To value too highly 5) Value 1) Misjudge 2) Overprize 
• (v. t.) To exceed in value. • (v. t.) To value excessively; to rate at too high a price.
O`ver·val'ue transitive verb [ imperfect & past participle Overvalued ; present participle & verbal noun Overvaluing .] 1. To value excessively; to rate at too high a price. 'To overvalue human power.' Holyday. 
[v] - assign too high a value to
to value too highly; put too high a value on: They should be careful not to overvalue the property.