According to ABUGames, which isnt the pricing authority on Magic but does at least have a reasonable set of listings for oversized cards, the foil oversized Gisela, Blade of Goldnight is the most valuable (around $250)
Machamp The 2-Player Starter Set included a 1st Edition Machamp that uses the shadowless layout
Sapphire and Steel can be a little trickier to manage if youre brand new to TCGs, due to its reliance on building up ink as quickly as possible - using the abilities of cards like Mickey Mouse, Detective, which allows you to add an extra card from your deck to your inkwell when played - to afford more expensive cards
@Quuador
Its like when Bill Belichick signs a football player no one else wantedno one would have stopped to think about the transaction if it were the Raiders, but when the Patriots do it, everyone takes an extra moment to stop and think "wait, is there something here Im not seeing?" Of course, this is the type of thinking that had me calling Daxos a format staple last time around, so take it with a grain of salt