Auctioning guardianship responsibilities seems like it will attract people or organizations who are primarily financially driven and looking to do the bare minimum, or who have to bid so low to compete that they don't have margin to do more than bare minimum. I would compare it to for-profit prisons in terms of incentives.

Just as with the foster care system, it seems like kinship is best, and next best is people who aren't doing it primarily for the money. Next best after that is arguably mission-driven nonprofits. Bottom of the barrel should be financially driven guardians.