I would try a millwork supplier, probably a higher end shop.

Glass Walls and Operable Partitions by ModernfoldStyles The recognized leader in space management design solutions serving New York, New Jersey and the greater Philadelphia area. I would start here.

Not sure what you mean by "faux" windows. Those garage doors have actual glass in them; they're probably frosted for privacy. Any garage door dealer/installer would be able to find these for you. They're pretty common.

My doors have a unique style which is not custom but were done by the same guy who built my cabinets. They complement the style of the doors. They started with basic doors that were relatively inexpensive and the end result was far less than a "stock" door from Trustile. I had gone to a Trustile dealer and priced out what was more or less what I wanted. I would imagine that any competent wood person could make the door for you. Of course - at least in my experience - by the time you actually have the door hung with all the appropriate hardware, it is still not cheap. Worth it but not cheap :-).