So, for example, I could tag all items based on their source ("Source A", "Source B", etc.), and get a breakdown in the Analytics tab ("Source A - £X sold", "Source B - £Y sold", etc.)
I don't think there is such a feature currently, is there? If not, is there some workaround someone could suggest? And finally, would this be a widely useful feature? It would certainly be useful for me (for example, I would like to be able to tag parts which come from my childhood Lego and easily see how much of this I have sold vs. Lego I obtained from other sources).