I bought two corny kegs in (I think) 2010 for $30 each. I frequently think about selling them back into the market at current prices since I don't have a keg set up yet. Except the hassle of cleaning them is keeping them out of the homebrewing market, for the most part. Right?
It's going to start getting cheap enough to find used 1/6th barrel sanke kegs and buy sanke connectors over buying corny kegs. I've seen the 1/6ths on craigslist for as little as $25. 7.5 gallon sankes sometimes float around for $20-50. Corny kegs locally are $45-60. I hear there are going to be 7.5 gallon slim kegs showing up on the market that may replace the 1/6th kegs which could push those out onto the homebrewing market.
And I can't help but think those are not legally owned. Add to that, a sixtel is more likely stolen from a craft brewery than a BMC.