When having my mini splits installed I pushed for an erv system in the bedroom. The installer had only ever done them in commercial units, and he hemmed and hawed about it, but I had two c02 monitors in my room showing it getting to above 2000 whilst sleeping. I've noticed a big improvement in how groggy I feel in the morning.

If there were good enough ERVs that could be installed by the DIY'er for about the cost of a cheap refrigerator (~$600 or so) then they would be more common.

I get that manufacturing the transfer plates isn't simple or cheap, but other than that one thing they're basically fans, they shouldn't cost that much.