I love the sting in the tail. When she wrote that sonnet, Millay was a professional poet who had sold her work:

"Or trade the memory of this night for food.
It well may be. I do not think I would."

I think she did (note: although not every "I" in fiction/poetry is autobiographical). :-)

Have you read her first poem, written when she was 15? It's a remarkably mature work.