Try a beer distributer, they will trade empty for empty because the deposit is the same no matter the size. I did it Saturday, traded two half barrels for two 1/6 (5 gal.) kegs. One of the sixths looked as if it was only filled once or twice.
On Tap: Caramel Ale, Mocha Porter II, MO SMaSH IPA Waiting/Carbonating: 12.5% Wee Honey II, 8.9% Old Ale, English Brown Ale, Lickah ESB, Mocha Porter II Fermenting K1: K2: Epic mead K3: TripSix On Deck: Caramel Ale Aging:mead Mead [bottled]:Oaked Wildflower Traditional, Mocha Madness, Blackberry Melomel, maple wine