Which Omastar 1st Edition do you have?
Same name, 6× the price: $3.42 to $20 raw. The difference is printed on the card — it is just not somewhere most people think to look.
World Champions Pack · #017
Check the set symbol in the lower right of the illustration, and the copyright year along the bottom edge. Those two identify the print run on every card that has them.
$20
67% gem
Split Earth · #029
Check the set symbol in the lower right of the illustration, and the copyright year along the bottom edge. Those two identify the print run on every card that has them.
$11
44% gem
Mirage Forest · #024
Check the set symbol in the lower right of the illustration, and the copyright year along the bottom edge. Those two identify the print run on every card that has them.
$6.64
100% gem
Advent of Arceus · #023
Check the set symbol in the lower right of the illustration, and the copyright year along the bottom edge. Those two identify the print run on every card that has them.
$5.00
40% gem
Awakening Psychic King · #016
Check the set symbol in the lower right of the illustration, and the copyright year along the bottom edge. Those two identify the print run on every card that has them.
$3.42
78% gem
We have no hand-checked note for these printings yet, so the guidance above is the general rule rather than something specific to this card.
Prices are raw market value. Click a printing for its full grading verdict — the gem rate, the fees and whether it beats selling raw.