Weber does not make a carry bag for the Q1200 portable grill, Airstream version or standard. So, after a great deal of research, I've found that the MAGMA Products A10-1293 is the solution. Very well constructed and quite sturdy. The grill fits perfectly, and there's plenty of additional storage for the hose, griddle insert and baby Weber utensils/brush. The bag should also accommodate the canister version of the grill, in addition to the propane cannisters.
$103 at www.magmaproducts.com
, and worth every cent.