Lewis & Short

aestĭmātor, ōris, m. [aestimo].

  1. I. One that estimates a thing according to its extrinsic value, a valuer, appraiser: frumenti, Cic. Pis. 35 fin.: callidi rerum aestimatores prata et areas quasdam magno aestimant, id. Par. 6, 3.
  2. II. Trop., an estimator or valuer of a thing according to its intrinsic worth (while existimator is a judge): nemo erit tam injustus rerum aestimator, qui dubitet, etc., Cic. Marcell. 5: justus rerum aestimator, id. Or. 41: immodicus aestimator sui, Curt. 8, 1 al.