I needed a bottle recently, and like you I don't like paying a rent.
Argon 5% CO2 Welding Gas Bottle Full | eBay
I used this guy, no rent, collared bottles so they can be refilled. He'd run out of a certain bottle that I wanted but comms was great and he gave me a knockdown price on a different option. Cylinder turned up by courier next day. Packaging was a bit battered but bottle was fine.