Ibn Ezra on Leviticus 27:16

ואם משדה אחזתו. שיירש עם ישראל: AND IF…HIS POSSESSION. Which he inherited with the nation of Israel.

חמר שעורים. וכתוב כי עשרת הבתים חומר ושם כתוב האיפ׳‎ והבת והנה זרע איפת שעורים בחמשה שקלים וזו גזרת המלך כדמי העבד: A HOMER OF BARLEY. Scripture writes, for ten baths are a homer (Ezek. 45:14). Scripture there writes, The ephah and the bath (Ezek. 45:11).⁵⁷The ephah and the bath are equal. Note, the sowing of an ephah of barley is valued at five shekalim.⁵⁸The sowing of a homer of barley is valued at fifty shekels. Thus an ephah of barley is valued at five shekalim, for an ephah is a tenth of a homer. This is a decree of the King regarding the monetary value of a slave.⁵⁹This is to be understood as follows: We find a similar divine decree with regard to the monetary value of a slave. A slave is valued at 30 shekalim. (Ex. 21:32). It makes no difference whether the slave in reality is worth more or less than the latter. Similarly with a field. A field is arbitrarily valued at 50 shekels per the sowing of a homer of barley, whether the field is worth more or less.