If you can get over the need for it to be an O/U, the very bottom gun on this list
http://www.doublegunshop.com/earle0.htm is a 20 Ga Flues (26in, IC/M) that comes in almost 2 lb lighter than the CZ, and at about the same price.
Alternatively, I think Kirby Hoyt has a couple sxs at reasonable prices which fit the light and short needs your companion has. Here's what I saw on his site:
http://www.vintagedoubles.com/inventory.php?sort=4&process=fullview&gunID=1661This is a 16 ga Sauer boxlock with LOP of 13 and 24 in barrels coming in at 5 lb 9 oz. for $1k.
http://www.vintagedoubles.com/inventory.php?sort=4&process=fullview&gunID=1492This is a French guild 16 boxlock with LOP of 13 5/8 coming in an ounce under 6 lb for $700 (but a little frost in the bores).
Hope this helps.