Bike Friday has had these available for some time,

http://store.bikefriday.com/index.php?cPath=3

But these aren't very price friendly, what was $50 is now $69.

Is there any competition? Exactly the same idea: split at the center, a shim covers both sides.

Also, ready-made road style bars with 26,0mm clamp diameter, or other styles of bars (trekking, moustache, etc).

One can undo the stem clamp and remove the bar from the stem, but often with bigger handlebars, this doesn't help trying to weave everything into 1 suitcase.