Unless they want to shell out the difference, they can stfu! It's not like you put someone else's dirty diaper on your kid. Just different stroke for different folks.
I buy new for the most part, but I just got 3 used snapless sbish for $30! I couldn't pass up only paying half price. And really I wouldn't mind buying used more often, but I'm going to be using the same dipes for 2-3 kids, so I figure I'm saving enough anyway.
Re: Used diapers