Funny I left him a message just before I posted this I havent heard back yet. But if I understand things correctly the coke style (pinlock) does not have the relief valve??? But the pics in his ad have relief valves.
If its this guy he has both listed on CL. This is about the best deal I've seen lately.
Pin vs Ball...well ball lock are narrower and have a manual relief valve with an air line style coupler, pin lock are shorter and fatter, have a twist lock coupler and a burst valve. So based on those items and my space i went ball locks. I like the manual relief valve and my kegerator is an old upright hotpoint fridge so space is a premium. Tall narrow kegs with a coupler that can be at any angle worked better for me. I can fit 4 ball locks plus the CO2 bottle. YMMV. Happy brewing.
You can also make friends with someone that works at Coke or Pepsi. I got 3 pin-locks from Coca-Cola for free. They were in great condition and nothing needed to be replaced other than the O-rings. If all else fails, you can go up to the delivery driver as he is dropping a shipment off at the grocery store and see if he'd let some of the tanks disappear. He might be willing to make a trade.
The local guy on craigs has both.. the pin locks are 4 - $100 and the ball locks are $40 apiece I have bought 10 ball locks from him in the last few months they are all in decent condition and I have only gotten 1 that smelled like the dreaded Dr Pepper... JJ