Been looking at goldstackers to try and value some of my higher premium coins I wish to trade. I noticed that the 2011 koalas are being sold for $42 whilst the 2014's are only $28. Both are said to be sealed although the 2011 koalas are labeled as 'buyback' What is going on here, please help me understand? Do the older coins gain this much value as they become rarer as they age? This doesn't seem right to me.
It just seems like a major jump in premium for such a short period of time. Already selling for double the spot value.