Yu-Gi-Ohs Western popularity came primarily from the 4Kids adaptation of the anime, which differed in some key respects from the Pokmon anime: first of all, Yu-Gi-Oh was much more directly a show about a product
Buy singles if your only goal is Cassiopeia SAR
There are three primary ways to win with tokens: You attack with enough creature tokens that your opponent cant possibly hope to block them all, You pair your token generation with Mirkwood Bats, Impact Tremors, Zulaport Cutthroat, and similar effects that drain your opponents life total as your tokens enter and leave the battlefield, or You have sacrifice outlets that let you cash in tokens to kill blockers and/or drain your opponents life, like Goblin Bombardment
Just like cards can decrease in price, they can go up
Get a balanced view of a card's value by comparing data from at least two or three different platforms, like TCGplayer for raw cards and PSA's guide for graded ones
#3: Laboratory Maniac #2: Jace, Wielder of Mysteries #1: Thassas Oracle The Father (Jace, Wielder of Mysteries)