My bad, I realize I misread your post - I thought you were trying to get a Gold Mario out of somebody for less than its worth, but I see you were in fact doing the opposite.
Still, despite retail value you can't really argue that Gold Mario and Lucario are equal in value after the fact. One of those was a one-time release in limited qualities in only one region of the world, and the other can still be found in abundance in some stores in the UK. Without even bring eBay prices into the equation, one of those is intrinsically more valuable than the other - I think he's truly the only exception to your argument. More power to you though if you're willing to downtrade to help someone out.
Were you expecting an American JPuff? I think she releases really soon in UK and/or Japan, but I could be wrong.
Right now, Gold Mario is exclusive to the US, but we don't necessarily know if that will be true forever. I mean, Europe is getting a lot of figures earlier than the US too.
Also where did you here Lucario can be found in abundance in the UK? Ike is the only "common in Europe, rare in the US" figure. Tons of collectors in the UK still don't have a Lucario.
My point here is that inflated Amiibo prices only exist so early because of scalpers trying to take advantage of sentimental Nintendo fans, not because they are genuinely worth that much. Amiibos are not comparable to say, a limited print comic book that is rare because they genuinely couldn't print that many (meaning it's forever discontinued) - Nintendo could easily print enough Amiibos to fulfill demand starting right now if they wanted to. But they're spacing restocks out, to keep us hooked and perceive them as rare, even though at the end of the day, all of them have no reason to be sold for more than MSRP. None of them have been discontinued completely yet. As I said, the only confirmation of a discontinuation we have gotten so far is Rosalina in the US. Technically, she should be the most expensive Amiibo in the US, because as of right now, no more US Rosalinas are planned for print in that region. Rosalina is the only one with any excuse to be sold for over MSRP in the US (as far as I know, Gold Mario has not been discontinued altogether). Most other unicorns have actually been confirmed for restocks in some part of the world (including those from Wave 4), and even the ones that aren't have not had a discontinuation announcement yet.
A product only becomes rare when no more are in production, not when it's merely sold out. Tons of things sell out, yet never sell for inflated prices. The Amiibo community is just rabid, and people exploit that for a quick buck. The figures aren't genuinely more valuable than MSRP.
EDIT: The best way to put is that Amiibos are not rare - they are scarce.
Amiibos are like vegetables - sure, they are scarce for a time depending on the season, but more can always be planted.
They aren't comparable to
real diamonds, which are rare and valuable - because those have a finite resource, and we can't make more. We can make our own version, but we can't make the original one that was mined from the Earth.