This is a completely self-contained engine, creating, sacrificing and pumping tokens at your leisure
As far as OPs question, the prices are anyones guess
Ultimately, this is a placeholder solution so that more time can be spent on fingerprinting and identifying headless browsers (EG: via how they do font rendering) so that the challenge proof of work page doesn't need to be presented to users that are much more likely to be legitimate
A Charizard was the rarest holographic in Base Set, so pulling one from a pack was like winning a mini lottery
Some cards care about mana abilities too, like Moonsilver Key, which can search for an artifact with a mana ability, or Battlemage's Bracers, which copies an ability unless it is a mana ability.
Phyrexia's mascot isn't the most popular creature to cheat into play, but its certainly relevant, and it's among the best 4-color commanders in the game