Air purifier -Child with Asthma

Tyler (left) has recently been diagnosed with severe Asthma. He is on daily preventer medication as well as Ventolin. He has been diagnosed with allergies and the main one is animal based. We need to purchase an air purifier for his room so he can sleep comfortable at night. With my specialist appointments ( arthritis and a possible sinus reconstruction) as well as his mum's tooth extraction under general anaesthetic we are unable to afford to purchase the purifier for at least 6 months. Your assistance will be greatly appreciated.
We don't like asking but with 4 kids, a lot of unexpected medical bills and the reluctance to get rid of pets we have had for years, this is the only way we could afford to purchase the air purifier.
Thanks in advance for any financial support or please share around.