I bought one of the cheapo, Chinese ones from Ebay. It was around $100.00
Works just fine. It even eliminated all the "baby smells" from a mini van. Spilled rotten milk, used diapers, rotting food. typical horror show. Even after a complete interior "wash" and extraction it still stank. Four hours of ozone and then letting it sit in my garage overnight got it all out. Plus during the ozone treatment I had a battery charger hooked up so I could leave the fan running to circulate the ozone through all the AC ducts and heat exchanger.