not much more than standard bifolds. Good quality bifolds cost around $14,000.00 to $22,000.00. It would have to be a custom window joiner not a big company like stegbar. You also need a sympathetic builder and in an ideal world an architect :) but otherwise a savvy and tenacious house owner.

I love that design. Brilliant.I am a builder. If you are serious about it, make contact for a quote.www.additionalconcepts.com.au

Nice design blending in the spaces from living room to outdoors environments.
Looking closely, you will find the doors also covered the counter top, to accommodate this type of design, the designer compromise the counter top with a bottom track. Losing shine the big spacious one piece counter top.
If you like to have more visually open spaces type of design doors for spaces and kitchen, even rooms.
You can find more ideas with award winning designs pictures and videos solutions @ www.HomeHubAndLiving.com/NewSpace