A calculator that can handle logarithms and trigonometric functions can be had for a few dollars second-hand (on ebay I see some for $3.50 with free shipping). Slide rules can be found at yard sales and flea markets for next to nothing.
Sorry to hear about your tough financial situation in the past. It’s a tragedy that kids go hungry in such a rich country. If an expensive calculator is going to be mandated in school, there should be financial aid available for it.