Looking for a cheap way to kill off roaches.
What type of roaches? If german roaches, the typical kitchen cockroach, we have much success with Dupont Advion. It is a gel type bait that comes in syringes. Low impact treatment, very safe. You can bait into cabinets without emptying the cabinets. Don't spray during the baiting period, as they sprays are repellent and will ruin the bait. Spraying and baiting is working against yourself. Us pros have non-repellent sprays, but when I advise homeowners for diy I would rather you not spray anything.
Otherwise, get a good identification of the species and get back to us. There are other bait for other species. Are they in the basement, kitchen, everywhere, etc.?