$3 + shipping a piece... would sell all 6 for $15 + shipping.
They look to be 1/4" barb size.
I bought a co2 tank and regulator and these 6 disconnects came with the deal. However, I have pin lock kegs, not ball lock, so here you go. I have no way of testing them, but the guy I bought them from owns a convenience store and said they just came off Pepsi kegs and worked fine. Some have normal scratches on them while one has a few deep gouges (second from right, on bottom), but it doesn't look to affect the performance. 5 are barbed, 1 is MFL.
Reply to this thread before sending me a PM. I will send them in order from least wear to most wear in the same order as the replies in this thread.