Nice pieces. My uncle was into colored glass collecting and had similar panels fitted above doorways in his house (the old pass through panels for air flow that was typically over doors.
Average cost today would probably be in the $250 fully framed. Diamonds are not difficult work to cut for a leaded glass maker, it's the more intricate designs that are labor intensive and cost $$$. Also, rare colors cost more, purples, reds, etc.
You could make these more "efficient" by afixing a plexi-glass or real glass plate storm window. to the outer side effectively creating a air barrier. Sunlight will pass through giving you the benefits of the colored glass.
