The current crown jewel, Mega Gardevoir ex 092/063, commands a staggering $664.01, while even mid-tier chase cards hover in the $100 to $300 range, keeping average top 10 prices well above comparable Japanese releases this year
Another example is Virus Beetle, a recent reprint in Edge of Eternities that gives you a 1/1 artifact creature on the battlefield while also forcing your opponent to discard a card--an inherent two-for-one
Just don't offer them pretending to sell some kind of ultra-rare misprint.
The limited number of Mega Dragonites might cause them to go fast in boosters, so you want want to order one ahead of time if you can
I was very disappointed at the lack of a postgame battle with him, other than random Challenge Cup encounters where he doesn't actually talk
At the least, you saved me having to buy a Legendary Jynx