Most building codes in US/CA mandate them since about 2015, so I'm not sure how niche they are (at least in new construction).
Depending on the (air) volumes involved, ERVs can be had for under CA$ 2000:
* https://gasexperts.ca/product-category/air-exchangers/lifebr...
* https://bphsales.ca/collections/high-quality-erv-air-exchang...
HRVs for less, but it's probably worth the extra few hundred for better humidity management.