My estimates the min cost of writing ordinary long form nonfiction well at various lengths in the US (not special stuff like poetry or advertising copy):
0-500 words: 5c/word
500-1500: 10c/word
1500-4000: 50c/word
4000-15,000: 75c/word
15,000-50,000: $1/word
>50,000: $2/word

