They now have a better Bally folding bag that goes into a pouch that becomes a pocket on Highlife Shop.
£230 from memory. Substantially heavier and sturdier than Longchamp le Pliage.
IMO Lipault does a similar one to Le Pliage but more sturdy and better quality. Price, if I remember correctly, is similar to LP but I cannot remember it folding up as well as LP.
An alternative is Tumi folding bag, the name of which escapes me right now. Just In Case bag or something like that. Tumi sale usually brings you good value one of those.