Book a flight with EasyJet either online or on the phone.
You have to do this next part ONLY on the phone.
Call up EasyJet on 0330 365 5000 and book luggage for ONLY THE RETURN LEG of your flight.
There is Glitch that automatically you will receive luggage for the departing leg as well!!
i.e you will now have luggage for BOTH FLIGHTS and you will only have paid for one way!
So you get FREE luggage one way OR you only pay 50% for luggage!!
I've done this before and it works!