All righty then...
I'm guessing Boris must have been hard up for money...
shareThis all came as a surprise to me.
According to the internet he was worth $20,000,00 at death, so I speculate he was okay in 1958. He was working regularly at the time, so money was probably not a problem. It was an eight day shoot, so why not take the money?
From IMDB trivia: In the final decade of his life, his "star power" was still so strong that the trailers for his films emphasized his presence rather than the plot or any other element of the film. In some of these trailers, he would be simply referred to as "Karloff".