The runaround pipe is perforated drainage piping with a diameter of around 150mm- 160mm.
That size diameter of pipe is quite expensive and generally only comes in large coil sizes of 50 Metres. So whilst Runaround prices might seems initially expensive (8ft = £18.50 not inc del) in reality they are well worth the investment.
If you just want the pipe, you could have a look in your local builder yards to see if they have any off-cuts or look on e-bay.