Respect for something you are or something you do is not the same as respect for something you buy.
There is an interesting couple of articles on the subject here:
http://thelastpsychiatrist.com/2012/01/what_would_you_do_if_...
http://thelastpsychiatrist.com/2012/02/what_would_you_do_if_...
I found it quite hard to extract anything from those articles. I think what it's trying to say is that if the ring becomes an issue then the relationship may be far from perfect anyway.
But then, I don't see how she'll be satisfied with any ring. Surely if a guy could sacrifice this much he could sacrifice just a bit more - so she may not be that valuable to him. I don't even want to start thinking about a guy who can afford a bigger rock suddenly showing up :D
Basically, the moral of the story, for me, was: 1) Avoid women who don't know their worth and require external confirmations; 2) Develop your own sense of self-worth by doing something worthwhile, then finding a like-minded woman would be easier.
I think.