Estimating rarity or number of units in circulation by frequency on eBay

[murple]

I really don't think that will give you an accurate picture of anything except rarity ON EBAY. It doesn't take into account the many sales and trades done over forums, web shops (AmigaKit etc), AmiBay, or CraigsList. Even if you got and combined statistics on all of that, it's only going to give you numbers from people who think Amigas are worth something and try to sell them to collectors. To many people, they're just old junk taking up space in the closet, and often end up in thrift shops or given away for free from people who are just grateful for somebody to "get rid of the junk." Let's not even think about stuff that just gets put in the trash.

Ebay also has a bizarre psychology that can artificially inflate prices on things that can be had elsewhere for much less, which can make things seem rarer than they are.

[murple]

I sort of hope you don't do this, orb. It may be an interesting mental challenge but for the reasons I already gave (as well as periodic fluctuations... I think you'd need to collect statistics over a couple years at least to take into account the way things sometimes seem to hit ebay in waves), I don't think you're going to get really meaningful accurate data.

Problem is the minute you release the numbers, every douchey seller on ebay is going to start using your rarity stats as a justification to jack up their prices.