Adam Clarke on Proverbs 31:16

She considereth a field and buyeth it -

5. She provides for the growing wants of her family. More land will shortly be needed, for the family is growing up; and having seen a field contiguous to her own, which was on sale, she estimates its worth, and purchases it a good bargain; and she pays for it by the fruit of her own industry.

6. She does not restrict herself to the bare necessaries of life; she is able to procure some of its comforts. She plants a vineyard, that she may have wine for a beverage, for medicine, and for sacrifice. This also is procured of her own labor. Whatever goes out brings its worth in; and barter, not buying, is her chief mode of traffic.