I use a local supplier, no rental/contract, just a deposit on the bottle and refill charges. We seem to still pay more down here in hte home counties than my mate with a similar setup oop-norf.I made a few calls today and it seems that low level use it is better to use Hobbyweld for cost.
Still not sure though as pressures seem to be lower and the more refills you need the more it sways back to BOC. I think I will keep my BOC account for Argoshield for the moment as I have 2/4rd cylinder left and pay the annual rental (hobbywelder BOC account so about half normal cost) and get a hobbyweld cylinder for the TIG. I'll then see how long a cylinder lasts and work out from there how often I will need one and either stay with Hobbyweld or get one from BOC and hand the hobbyweld back.
I have a couple of weeks before I have time to do anything with it anyway so not in a massive hurry at the mo.