Like most Pokmon cards, the value of Landorus depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Lost Origin)
It has limited uses, but how many times did you really need to activate your Resonator anyway, barring specific infinite combos
Unfortunately, the only items worth a million dollars are the items that are so rare a collector has no choice but to pay a million dollars
General advice : Set alerts on TrackaLacker or Discord communities
Ok Scrap Chimera [Gold Rare] MGED-EN010 (YuGiOh Maximum Gold: El Dorado) Details All prices are the current market price
Collectors may begin their TAG Grading experience at any time here - TAG's TAG X service (1-10 Grading with DINGs reporting) and TAG V service (for encapsulation without grading) are available to collectors at all times