goto goodwill. buy used, not new. Walmart recently did a collaboration with an outdoor company (they bought out) and their gear is garbage.
Get a tarp and learn how to use it now and then figure whether you want to use a hammock or lie on the ground with it.
What state are you in, because you may not want to be there when winter comes around.
Unless you have steady access to water, get a Sawyer water filter
https://www.rei.com/product/103050/sawyer-squeeze-water-filter-systemThese are rated for like a gazillion gallons and have a lifetime warranty. Mark a clean bag and a dirty bag. Only problem with them is the bags kind of suck but those can be replaced with others. Also, don't get smaller sizes. They clog easily.
Get a water container. Gatorade bottle is fine. Something you can boil with as well.
I don't know if you are a fishing retard or not, but you can get a lot of food off that because 250 is not a lot. You probably want twice that to start, so you are definitely in the broke category. I'd also check out military surplus. Get some bic or a ferro rod.
learn to love peanut butter. t here's other threads here for cheap and easy food.
get ready to apologize to your mom when your plan falls through in a week.