I was really fortunate in this area. I had a pump able to deliver 150litres a minute and so wantes 1 1/4 " to help deliver this. So went to the local "Range" shop, sold per metre at £2:39. Measured out 6m and the assistant wrote 4m @ £2:39. Went checkout and cashier put it through at £2:39 for the whole lot. Didnt even question the obvious that there was more than 4m. I told her it was per meter but she wouldnt have it! She even checked with customer service who comfirmed with her. So on the system you could get upto 25m for only £2:39.
So if you have a "Range" with unlogical cashiers, you would do well to head there!