""$1 and $2.50 might not read as much different to the purchaser’s gut sense of value. But $2.50 and $5, say? Might be enough for someone to just opt for free." That might be so, but it's not the right question. Instead, you need to figure out if enough more people opt for free to cancel out the additional revenue. Because you want to maximize overall revenue, not number-of-paid-copies, or even revenue-per-paid-copy." - Michael R. Bernstein