While many of the commercially available devices can be expensive, there are lots of inexpensive options. People are using $10 IR lights for CCTV to target small spots like the mouth. You can upgrade to a larger $45 one which people remove the glass from so you can press it directly against your skin. There are also visible light bulbs available on amazon for $25. This is the kind of stuff I'm using. Old studies used lasers until it has been proven unnecessary. LED's can get to specific wavelengths and are cheap.

There are over 400 new studies being published on photobiomodulation each year. There are growing communities of enthuseists on facebook. One of the key things you need to figure out is your dosage at a distance and penetration depth into your body to achieve a hormetic effect. Red light penetrates deeper than most lights and IR goes further than that. In the doses that LED's offer, it is safe if not beneficial for cancers. There is a huge amount of literature on the topic and I'm just scratching the surface. Let me know if you want to hear more.