St Albans - Farringdon?

Hi, I am a student, traveling this route daily...WHAT IS THE CHEAPEST WAY? I am currently driving by car to Hendon Central every morning where I get the tube with Oyster �20 a week + petrol, still too much... There's a train next to my door going to Farringdon, but I cannot pay �250 per mont, it's stupid and no discounts for students...please help, any tips, tricks, experiences...or is there someone driving every morning? We could go together and share the petrol or something...please help, thanks a million:)