I followed the below 10l batch
1kg Maris Otter (about £1.50)
One packet of hops (any you like - EKG, Citra, Amarillo, Galaxy, Fuggles, First gold etc) (About £3-4, but you will only use 15g of the 100g, so cost is around 50p)
One packet of yeast, 3g dried yeast is enough. (50p ish)
Method...