I forget where it was on the forum, but this question was asked semi-recently about someone buying autos from a Pokecolor auction on eBay and what you described is what the user was told from Pokecolor. I’m not sure if the amount they paid changed in the end, but I don’t remember hearing follow up complaints, so any potential price increases may already be baked into the price that you see when you pay.
If you’re able to, it may be worth reaching out to potential sellers and seeing if they have any idea.
Edit Found the post I was thinking of. Mind you, this was in January so information may have changed. It also appears when @gdark made a purchase they shipped it to their vault; not sure if that changes things if you don’t ship a purchase to a vault.