I can get a 6kg propane refill for just a bit more than the B&Q price!
I've just been up to the local garage and they have 11Kg propane for £24, or in other words over 27 times the gas for double the price of a 400g canister. I think it's fair to say that the canister bought yesterday will probably be the last. I just need to get an order off for the pipework and regulator.
And although it's been well noted here on the forum I was really surprised how quickly the flame cooled off, I think I managed to get three beads done last night (I'm still just practicing), the fourth just ended up half done and I gave up. I take it that this doesn't happen with bulk propane and the flame stays a constant temperature.