Has Lego Box 5508 been discontinued?
It's possible the set has been discontinued. Since its release in 2010 there have been many other Brick Buckets released under the 'Bricks and More' series.

For example; the 10663 Creative Chest released in 2013 is available in a similar price range but is more limited to building vehicles (no doors, windows and roof tiles for buildings). 



If your kids are more into buildings and there are no other Brick Buckets in stock you can suplement your LEGO collection by purchasing the Doors &amp; Windows pack as well as the Roof Tiles pack.