If I see Gold Mario/Silver Mario lying around at a local store, I will definitely pick them up for the sole purpose of keeping them boxed and reselling them in the future, maybe in two years or so. They would look nice in my room until the time comes too.
Normally I open Amiibos, but I'll make an exception for them. They are literally just Smash Mario/regular SM Mario functionality wise, and I intend to get both of them and open them for use. That, and I can't see many people in Ireland caring for them, let alone caring for the Mario Amiibos over the Smash ones (since Smash includes non-Mario characters that are popular here, like Sonic).
They are basically marked as Limited Edition, so they're asking to be used in this kind of way. If it doesn't do anything different to the other Mario Amiibos, which are distributed in abundance, I see no reason to open them.
That being said, I will likely never see them. Apparently Gold Mario is a regional exclusive, to the US.