It certainly doesn't make too much sense to me. I know why it's important to the recipient, but the cost shouldn't matter. I hope women aren't putting stock in the cost on the diamond over the symbolism. If that's how you prove the standing of your groom, that's a tad depressing.
 If they are then they're headed for a miserable marriage. If a person makes money the central issue for day one, that's headed for disaster right away.

That said, I know some guys who got other arrangements. The first had a girlfriend who loved rubies. I don't know how much they cost, but aren't they a little less, at least?
Funny you should say this, because my wife loves rubies. In fact her wedding ring (that complements her engagement ring) has rubies. I've actually heard women say things to her like "I don't like mixed stones on a ring." She just looks at them and says, "it's a good thing this isn't your ring then." She's very proud of her ring!
The other guy I know had an odd arrangement. Since the girl knew he couldn't afford a ring, she made him do 100 hours of community service instead.
My mom and her second husband bought each other stock! But then, my mom has always been very un-"girly"!
_________________________
-Jeff
Rome did not create a great empire by having meetings; they did it by killing all those who opposed them.