Got mine yesterday, my verdict is if you like retro systems it's well worth getting at £77 I paid but gone back up to £100 now.
The Core Grafx Mini that we get in UK/EU is arguably the best version as it has the small form factor of the Japanese version and the auto fire joypad from the USA version - the Japanese version looks the best still, but that's around £120. The Turbograpx 16 is almost pointless as a mini as it's so big, definitely avoid that version IMO.
UK/EU version seems to be the best one overall in terms of actual utility, so likely to still be highly collectible.
At £77 it's good value, you get a good controller with USB so likely can used for PC too, a smart repro mini console that looks great on a shelf, plus well over £100 worth of virtual console equivalents, including classic games like Castlevania Rondo of Blood and a ton of great shoot em ups.
You get 52 games not including the non-translated Japanese ones that are unplayable unless you speak Japanese like Snatcher, but that's a tiny fraction of the games that simply didn't have an English version in the first place. Better to include than not at all I guess.
It also includes 5 hidden games - 3 arcade versions and 2 totally unmentioned games including Twin Bee.
Technically it surpasses the superb Snes mini by including quite a few PC Engine CD games with CD audio, it's pretty amazing how much they squeezed out of a 8 bit machine over the years back then, albeit with a 16 bit GPU.
You also get so many games it's a viable total console in the way the Snes mini isn't with only 20 games (albeit a higher quality overall than most PC Engine games.)
Overall, at £77 seeing some of the hugely inflated prices for GPUs and other mini consoles, this was a great bargain, just like the Snes mini, the save states and official branding make it the best way to play some of these games barring the original consoles.
This was a great review I found that covers a lot of the details like hidden games and regional variants:
https://tiredoldhack.com/2020/04/25/pc-engine-coregrafx-mini-review/