Writing isn't exactly the best-paying career. Sure, there are people like Stephen King and J.K. Rowling who rake in the dough — but they're definitely the exceptions. Unfortunately, the ghostwriters who wrote the Hardy Boys books are among the many writers who didn't get paid particularly well for their work.
Ghostwriters were paid $85 per book when the series launched in 1927. That would be close to $1,300 in today's money — not too bad, but considering the many millions of copies the books eventually sold, not even close to being fair. According to The Atlantic, the pay got a little better over time, and in the 1980s some ghostwriters were making $5,000 per book (which would be about $15,000 today). That's not bad for cranking out a short kids' book — but when you consider the sales these books generated, it starts to look much worse.
As Salon points out, the first Hardy Boys book, The Tower Treasure, has sold more than 70 million copies since its publication. The ghostwriter, Leslie McFarlane, earned about $4,000 total. If he'd been given a standard royalties agreement, he would have been a millionaire. McFarlane never complained, though — he told an interviewer, "I was not swindled. I accepted the terms of Edward Stratemeyer, and the importance of the money was related to my needs."