估价 is a separable verb (离合词) meaning 'to appraise or evaluate the price/value of something'. It can also be used as a noun to mean 'appraised price, valuation'. As a separable verb, you can insert a measure word or other element between 估 and 价, e.g., 估个价 ('make an appraisal') or 估一下价 ('do a quick valuation'). The thing being valued is usually introduced by 给 or 为.