As much as I agree with the "forget the woman who wants an expensive diamond" attitude, is that realistic? Many of the girls I know say they'd marry a guy despite the ring, but they'd be disappointed if they got a "cheap" one.
I also heard "never get a diamond from Macy's or another department store" and "never buy Zales", only get diamonds from "Tiffiany's" (and other undoubtedly expensive jewelry stores that I've never heard of). Her boyfriend is saving for a ring that'll cost half his starting salary. Granted, they are an extreme case (I presume they are wealthy), but I would feel horrible if my girlfriend was disappointed by the ring and just kept quiet about it.
Why can't girls like practical things, like a big screen tv and a pool table? Hell, I don't carry one week's salary on my entire body, much less two months salary on a damn finger.