I don't think you're wrong for wanting a ring that you're going to love wearing for the rest of your life. The challenge is to find one that both you and your FH love, that you both feel is worth its price.
I also think it's great that he asked you to choose. There may be some couples where the guy can choose the ring and surprise the lady, and they are both satisfied with it, but I think most women have fairly strong feelings about what they do and don't want their E-ring (and wedding ring) to look like, and men are not clairvoyant!
You mention a certain size diamond, but (as you probably know, but your FH might not) diamonds of equal size can vary greatly in price, according to clarity, color, cut, and just "personality," not to mention the setting. I started out wanting a diamond around 3/4 carat, but when I found the ring I was happy with, we had to go with a much smaller diamond because of price. In a way I would have liked him to say, "Oh, well, let's go $1,000 over budget and get you the size diamond you had in mind," and I knew that if I insisted, he would have. But I didn't think that was the right way to treat him, he knows a lot about jewelry and was already deferring to me by buying from the company that I chose. He has a friend who runs a jewery business and would have liked to buy there, but his friend could not come up with anything that I considered acceptable. OK, sorry, I am getting off the subject -- My point is that the smaller diamond we ended up buying looks "right" in proportion to the rest of the ring and my hand, and it's a very high quality diamond with a certificate and everything.
I also was careful to evaluate how the engagement ring looks with the wedding band, because the E-ring gets worn alone for just a short time. Now that I have both rings on, I'm extremely happy with the choice.
Money was a touchy subject for my husband and myself when we were getting engaged, and I can imagine it might be that way for you too. I would advise you not to shy away from those difficult conversations about money and priorities. It may be scary (I know I was raised with the idea that you don't talk about money!) but if you go ahead and get married without knowing each other's feelings about money, that's even scarier. And if it's in any way reassuring: now that we're married (4 weeks) it has gotten much easier for us to communicate about finances.
Eve T
June 20th 2008 I marry the person who "gets" me!! 
