Keep in mind though, that lots of technical book sales are made to employees of companies that may give them an annual budget for such things, or might just req

Keep in mind though, that lots of technical book sales are made to employees of companies that may give them an annual budget for such things, or might just require a quick "Yeah, sure go ahead and expense it" type of approval. I agree that $50 isn't nothing to an individual, but it is approaching nothing to a large company.