Food and equipment becomes or become expensive. I am not sure if I should use become or becomes in this sentence.
If you think that grammatical "rules" should dictate how native speakers of the language should use their mother tongue, then there is no doubt that since food and equipment are collectively plural then the verb should take the plural form "become".
If you are interested in how the language is actually used by its native speakers, the question here turns on whether the phrase "food and equipment" is likely to be heard as a single entity. If the phrase strikes the listener as a single thing, then "becomes" is OK. If not, not.
Now "food and drink" certainly go together. So "Food and drink becomes expensive" might be OK.
I am far less sure about "food and equipment". To me that sounds like more than one thing. So go for "become".