Oh, Trish! Just reading this, sweetheart! I'm so sorry. You and Barney are in my prayers, my friend.
I can imagine how heartbreaking this must be for you, and how hopeless it must seem at the moment, but you must not lose hope! Yes, it is possible that he has flown some distance from where you live. And that's what all of those fliers are for. But just as some birds have been recovered a town or two away, many others have been recovered from the same neighborhood or one adjacent. All that you can do, Trish, is to cover every possibility. Reaching out to vets, police precincts and firefighter houses both locally and the next few towns over helps to cover your bases. But so does putting a "feeding station" cage outside your house.
Don't assume he won't circle back your way. Whether he has some sense of where home might be, or if he's wandering aimlessly, the possibility exists that he might find himself in your area once again. If his cage can be moved out into the open, with Madge doing her flock call for him, that might be enough to guide him home.
The possibility of his recovery isn't as remote as it might seem. Mark went out looking for one lost African Grey and found three instead! It's possible, my dear friend. Please don't lose hope.