Does size really matter?

Last year when I agreed to move my family into the garage I had so many conditions.  One condition was that we would have designers help us.  We got that figured out pretty quickly.  Another condition was that I wanted bifold windows.  Having lived in New Zealand where this is relatively common, I was dreaming of one day having a kitchen like this:

There is not one thing I don't love about this kitchen, with the possible exception of the hardware, but I'm sure that we could all live together quite happily.  Unfortunately, once we started actually pricing bifold windows, the cost put them out of reach.  (In one estimate, the screen alone was $1700!) So the challenge then became mimicking this feel without the hefty price tag.  I settled on 3 casement windows with a transom over the top for extra light:

When closed they'll look similar, but open they won't be quite the statement.  Our builder recommended a french casement window as a possiblity:

When closed they look just like casement windows, but when open, they don't have the center bar and will have the feel of a bifold window.  We had two great options for alternatives, even if not quite the grandeur of the real thing.  The downside of the french casement is that it's only made in wood, which would mean much more maintenance for us long-term. It didn't knock it totally out of contention, but we wanted to see what the prices were in relation to our current 'opening' of 76"wide x 58" tall. Here's a picture to jog your memory.

It turns out that the french casement windows were only 58"x58".  I wasn't willing to lose over a foot of light and thought that sidelight windows would look stupid.
This brings me back to my initial query: does size really matter?  It turns out that when it comes to windows, it really does.  76" wide is a non-standard size and that made the windows almost $1000 more than if we went with a 72" width.  I wasn't willing to lose 18" of width for the french casement, but I am willing to lose 4" of width for the 3 casements in order to save that extra money.
This entire build has been about eeking out savings where we can while trying to save the design intent.  The only reason I found out about this potential cost savings was because I happened to have a quote from another company that was significantly cheaper than the one my builder gave me- but it was initially set with a 72" opening.  When I called and gave them the corrected measurements their estimate also shot up.  We've been doing a great job of finding savings and ways to cut where we can, we just wish that our builder would've helped us out a bit on this one.  I find that I'm walking a tight line between trying to stay out of the builder's way and not pissing him off, and getting myself involved in every detail so that I can try to save as much money as possible, seeing that Scott and I keep finding cost savings.  Fingers crossed by the end of this he still takes my calls.