A Japanese Shiny Treasure ex box generally runs about $90$150, while a single chase card like Mew ex #347 can cost about $360$510 on its own
Sorin, Imperious Bloodlord Current price: $14 Another victim of card bannings, Sorin, Imperious Bloodlord would have been one of the biggest cards of this set had Rakdos Midrange not flown a little too close to the sun and gotten smacked down with a Pioneer ban
You can see an example in the third picture
As for the all-timers: Undertale , Chrono Trigger , Portal and its sequel, What Remains of Edith Finch and Fallout New Vegas are up there for me
Image - Opened 2 Player Starter Set Base Set 2000 printed in the U.K
Wizards accidentally printed not only one of the most broken combo engines ever but also one of the most miserable