It all comes down to printing costs and what percent they pay on the profit. Lulu seems to offer a higher percentage to the author as a metric to your question.

It all comes down to printing costs and what percent they pay on the profit. Lulu seems to offer a higher percentage to the author as a metric to your question. Interestingly, Amazon has like 2.4 billion site visits vs. Lulu's 2 million, so the author would stand to make more on Amazon simply in volume of sales potential (1000x more).