you want to use boric acid, not borax.
If you have a biodiesel supplier near you, you can get it cheaper.
get the finest micron you can, if only granules at the biodiesel guy, then buy the roach powder.
you need citronella plants, not lavender.
lemon grass, cantnips, chrysanthemums. Thyme, oregano , and the mints help too.
block any windows cut into doors, so bugs don't come in when you open doors at night.
you also want to get a sprayer, mix boric with a little liquid soap in it, and some cinnamon oil, and spray it up underneath porches , into plumbing holes in the walls, and around any animal housing.
good luck !