While certain factors can change things, the market price of cards is often considered to be based on the last few cards of the same type and similar condition sold on eBay
Okidogi ex 82/64 Loading
Behold the Multiverse Instant speed, able to be played later with the Foretell ability, and letting you Scry 2 before drawing to set up your draw, Behold the Multiverse is an extremely versatile way to draw 2 cards for what you want to pay, when you want to pay it, and even get up 4 deep if you need to
In order to meld two cards you need to both own and control a meld pair
Such cards can bring some money to buy a normal card
Similarly, if the move is strong against one of the opponent's types but weak against the other (such as Razor Leaf, a Grass-type move, used against a Gyarados, a Water/Flying Pokmon), the move deals normal damage