1k per foot you pay for Nana walls and even they start at about $600-800 per foot and I'm sure it's a much better door and system, and even so your door is 7'6" so 1k per foot should only be around 8k.

Something doesn't sound right unless there is an additional 6k in bells and whistles which also don't make much sense especially the product is from Andersen or Pella manufacturers.

That said, I understand you have a 14-16' opening and you want the bi-fold to open up the entire opening and there is something to look at it would worth the money...

Spending 14k to open up a 7' opening I can't see that cost to justify it's purpose unless of course the money burn a hole in your pocket than its perfectly fine.

If I to hit a million dollar lottery and told my wife lets get a 14k door ... she would say lets get a 3k door and a 10k Kohler Numi High Tech Toilet or take a nice European vacation. lol Just saying.

Have you looked at these as an alternative? http://panoramicdoors.com/

That's what I'm getting priced out for my place. They're supposed to be cheaper than bi-fold, from what I've heard (although they're still going to be expensive - they are still large windows). I like the way they work better than bi-fold.