I moved into an apartment with my girlfriend about 7 months ago and we had the same problem. Cooking everything ourselves was causing our grocery budget to balloon out of control because we had nothing in the pantry, no spices, no oil, no sauces, nothing. So every new dish was an extra upfront cost that would really only get used one time and then go back in the cabinet.

After about 3 months, it somewhat stabilized now that we have all the staples and it is cheaper to buy raw and cook ourselves, especially if you buy in bulk and freeze leftovers.