No need for 2012 “as far as we can tell” claims or $7,000 claims: Elsevier kindly make all this super easy to find: It’s $500 to $5,000, with lots at ~2,500 (see below). PeerJ (of which I am a paid-up life member because I like the motivation) is now charging $1095 per paper.
Competition will tell, but I am guessing that we’ll end up in publishing like we have in Taxis: much lower net cost everywhere, but still closer to what they were than to zero.
PS: re “Individual funders switching to APCs does not result in canceled subscriptions”. Agreed, but I hope I never claimed it would?
PPS: When Cortex went paywall-free, they noted “we can only do this if your library doesn’t cancel its subscription”. That’s the real challenge: going CCC AND switching (not losing) the funding stream devoted to journals and libraries to open the journals to the world, and to re-use and re-mixing.