Not worth a thing, ship it to me and I'll dispose off it for you. J/K they are worth whatever someone is willing to pay for a 5gal sanke or whatever the deposit is at a beer/keg store. I would guess $30 and up depending on it's condition and whether someone has a sanke coupler or not. easiest way to figure it out, call your local keg place and ask them what the deposit is on. 1/4 or 1/6 barrel keg, and price accordingly. Hope that helps.
Primary: Belma Blonde, Narzen, "2-buck-chuck" wine
On Tap: Workaholic SMaSH Blonde, Brown, Cider
Bottles: King Czar Stout, Wee Heavy Scotch Ale, Christmas Lager
Aging: RIP RIP Stout (Rest In Peace Russian Imperial Stout)
Next batch(es): "two-buck-chuck" wine, Oktoberfest, Belma SMaSH