I came across this case at a store recently, made by the design company Umbra. They call it a Bungee Micro, but I think it looks suspiciously like an inro, like this one from the Boston Museum of Fine Arts:
There's a small elastic cord than runs up internal cord channels and joins at the top of the case. The upper portion lifts as a lid and then fits back into place with the retention of the cord. There aren't stacking compartments in this one (hey, it's under 6 bucks) but it will fit money and a set of keys. The neck cord is also the perfect thickness to fit into the himotoshi of a netsuke, for suspension from your belt. There are business card holders and mp3 player cases in the Bungee line too.