Having a large space can help, but you really only need a small plastic box, some vermiculite, some wheat flour, and spores

edit: and also you probably want gloves and a mask and to be super duper careful with disinfecting anything that might come near your substrate

edit again to add that buying spores online is legal in most states, and that there are sellers on etsy who have reasonable prices on spore syringes.

For what it's worth, I do this hobby in a small flat with no issues.