If you have a garden grow legumes and other cover crops, compost them, and use that. If you live by the coast gather Kelp for Kelp Meal, use that. Do you know anyone with pet chickens? chicken poop is gold. Think like a biodynamic farmer who has to get everything from local inputs.
Or you could potentially mail order Gaia green and other dry amendments internationally. I have never tried but maybe it's possible.
Best of luck