OEM (genuine) replacement filter pack (includes washable carbon filter and HEPA filter) for the Winix 5500-2 (filter "H"). $52.52. Designed to last 1 year under normal conditions. This is one of the less common filter sizes and it hardly ever gets cheaper than $60 or so.
Lowest price ever according to camelcamelcamel.
https://www.amazon.com/gp/product/B01JLT1OR8/
Same price at Walmart:
https://www.walmart.com/ip/Winix-…2/53083629
http://www.amazon.com/gp/product/B01JLT1OR8/