The Pulpit Commentary on Genesis 33:19

And he bought a parcel of a field,—literally, the portion (from a root signifying to divide) of the field—where he had spread his tent,—and in which he afterwards sank a well (cf. John 4:6)—at the hand of the children of Homer, Shechem's father (after whom the town was named, ut supra), for an hundred pieces of money—or kesitahs, the etymology of which is uncertain (Kalisch), though connected by some philologists (Gesenius, Furst) with kasat, to weigh; translated lambs (Onkelos, LXX; Vulgate), but believed to have been a certain weight now unknown, or a piece of money of a definite value, perhaps the price of a lamb (Murphy), which, like the shekel, was used for purposes of commercial exchange by the patriarchs (Gesenius)—probably a coin stamped with the figure of a lamb (Bochart, Munter); but coined money does not appear to have been of so great antiquity (Rosenmüller, Wordsworth, Alford).