Dried fruit and nuts like dates and raisins you can get in their cheapest, dirtiest form, and sanitize. Just boil a kettle full of water, put the fruit in a colander, and pour the boiling water onto the fruit, while you toss it. This not only cleans the fruit but rehydrates it, so that it improves in quality. With nuts you just do the same thing, then toast lightly on a baking sheet in the oven after they have dried. I had a rather nasty cockroach problem in my flat until recently.
Cheap flats have such problems.
Russian poisons were hard to find and ineffective. Then I got a cat. I no longer have a cockroach problem. Volunteering to be a cat sitter is consequently an inexpensive method of pest control. You can often volunteer to keep the cat of your landlords while they are away for the cost of cat food, and get one with the flat, for free.