All shinies go for $200 - $400 for a set where you can pull ~2 shinies in a box… so they aren’t going for cheap relative to the pull rate & pricing of 36 packs. They’re going cheap for what they used to be worth because there used to be so few PSA 10s until recently… I’m surprised a lot of people are surprised about the price drop.
I’ve said that CoL shinies will become increasingly popular for a while now due to a variety of factors, so I personally think the price levels at this point are sustainable… the question is whether it’ll continue to grow and/or pick up greater momentum, to which I have my own hunches.