You guys may already know but air liquide is running a pilot scheme in the midlands for 5 & 11 Ltr cylinders which they are calling Albee see http://www.albeegascylinders.com/cylinder-specification.html I'm in plymouth and the local agent hadn't heard about it. Speaking to one of the customer service guys it's being rolled out across there network. Prices for a 11 Ltr is £130 - £170 depending on the agent for pure argon purchase then just swap cylinder and pay for gas, they come with a built in reg and flow rate valve. I personaly am going for there Altop rental which is a 300bar job with 10.1 cubic metre but is only 1.2 metres high. sorry if i should have put this in the suppliers list but i didn't want to sujest them as a supplier rather they are trying something different which may suit some people.