> then their value follow a bell curve up, when they getting > sparse and therefore become collectible. Heck, there a > still PPC macs sold for up to several 100$.
At least on eBay Germany, G5 PowerMacs that were introduced at a basic price of 2000…3300 USD/EUR (depending on model) in 2005 have been going for 134 EUR on average during the last 3 months and have been going for about that average price for some years. I bought 2 of them for 6% of their introductory basic price. The 'bell curve up' for these models has yet to start it seems.
> Intel Mac minis reach 500$ for a corei7 from 2012.
On eBay Germany, for the 54 machines of this exact type (introductory basic price: 800…1100 USD / 830…1130 EUR, depending on model) that were successfully sold during the last 3 months, the price distribution is as follows:
500 USD would be about 410 EUR currently, so with 15% of the machines selling higher and 85% of the machines selling lower, that's way above the average price here in Germany at least.