Cheap as in new-but-cheap? Mine was old-and-cheap - a big rusty industrial unit. For a new one, I can recommend a Clarke 135 turbo - lasted me for a decade and then I outgrew it. I get my gas from SDL Minorfern who are a local motor factor's - a big exchange bottle costs about £40 per fill, with a £70ish deposit. The bottles are branded Hobbyweld, whatever that means. Much cheaper than the little disposable cylinders, but still without having to pay a weekly rental. Probably the sweet spot if you're doing intermittent biggish jobs.