Sure, it costs eight mana, but considering it has delve, which lets you exile cards from your graveyard to pay for its cost, if you could get seven cards in your graveyard, the reward is a sorcery-speed Ancestral Recall legal in formats like Standard and Modern
In other words, there may be more than one bogus or illegal item driving up the bidding in this auction.
Indeed, she is currently the second most popular uncommon commander, only behind Syr Konrad, the GrimSyr Konrad, the Grim, who shows up in 34,744 decks, although she's actually beating his 1,384 decks as a commander rather handily
The price tag is surprising, given that the main card is a strictly worse, color-restricted Panharmonicon, which itself is only just over $5