Cheaper still, by a factor of, ooh, at least lots : Self Raising flour (2 cups), a tablespoon or two of butter (rubbed into the flour), enough milk to make the above into a dough. Kneade on floured surface, roll out to whatever shape/size your pizza tray is.
A bit of tomato paste, Mozzarella cheese, and any pizza-esque ingredients of your choosing. Add sweet chilli sauce to sliced zucchini, brocolli, capsicum, carrot for a magic vege pizza.
30 mins in the oven at 200 degrees C and voila - magic pizza. Magic in so far as it's way cheaper than the pre-made stuff, and way tastier. And you can make it and eat it and clean up within an hour, if you're efficient.
Last night I made a satay chicken pizza. Shop-bought satay sauce (OK, so I cheated) in lieu of tomato paste, topped with little chunks of chicken (cook it first), snow peas, and mozzarella cheese. Delish.
As for other ways to save - there was (probably still is) a newsgroup called alt.frugal.living I think. It had such startling revelations like using a washing line is cheaper than using a dryer ("My power bills went down by so much! Wow!") but it also had genuinely useful stuff from time to time.