What did a medieval merchant widow earn?
About 100 pounds a year from trade.
About $24,000 a month in today's gold.
A month of that pay weighs about as much as an apple in gold.
Sold the queen a robe, traded wool in her own name, and sued the Crown five times. Won.
Where the money came from
Rose was the daughter of Thomas Romeyn, a rich London wool and spice merchant who was mayor of London in 1309. She married her father's business partner, John of Burford, who, like him, was a spice dealer. When John died, around 1322, she took over the business and ran his spice trade as well as her own wool exports. John had lent Edward II money for his war in Scotland, and Rose asked at least five times for it back; the crown agreed only when she offered to have it taken off the tax on her own wool. She was rich enough to lend the prior of the Hospital of St John 1,000 marks in January 1325. She also ran an embroidery workshop. On Edward II's orders she made a church cloak decorated with coral, sent to the Pope as Queen Isabella's gift, and earned 100 marks for it; in May 1317 the king paid her fifty marks, half of what he owed. She owned houses in London and estates in Surrey, Kent and Sussex. Her will of 1329 left forty shillings to the work on London Bridge, houses in Bread Street and the farm stock on her manors to her son James, and money for prayers in a chapel she had built. Her loan to the prior alone was ten times what the king paid for her cloak.
Sources: en.wikipedia.org · edwardthesecond.blogspot.com · british-history.ac.uk
What a merchant widow's pay bought in 1350
a year's cottage rent: less than a day's pay
a hand-copied book: 3 days' pay
a year's food for one adult: a week's pay
Harlech Castle: 82 years' pay, more than a whole year of it
the ransom of the King of France: 5,000 years' pay, more than a whole year of it
Every price of 1350, with its source, is on the prices page.