In my limited experience, Amazon has been flawless on price guarantees and on returns. Amazon may have some evil aspects, but they are not cheap chiselers. I made my first purchase from Amazon in 1996--in part because of an interview in which Bill Gates said he'd tried them and they seemed "very reliable." I used the Lynx character-oriented browser to look up the book and placed the actual order by phone. So far, they've lived up to Bill Gates' testimonial.
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.