Cost of van life?

I've always wanted to do van living or have a tiny home. Or both. But I'm currently in a situation where money will forever be tight. I can't work much and so I've been wondering how much van life typically is per month? I was thinking of using my current vehicle as a trade in so ignore the initial cost of buying the van. How much does everyone typically spend to live in their van? I'm talking food, gas, insurance, parking, and all other needs unlisted. All input is extremely appreciated!