I tried to explain the UK Amiga price bio-rhythms before. It all surrounds the age and lifestyles of the Amiga users.
The first dip in Amiga prices (the lowest) was between 1997-9. The market was flooded by Amiga's as everyone wanted to sell their hardware before it lost all of it's value (to buy a Voodoo accelerated PC to play GLQuake!). At the low point you could pick up A1200 accelerators for next to nothing!
Between 2000-1 the market bounded back, nostalgia for retro had kicked in driven by the uptake of broadband and the internet. Forums such as this gave the former Amiga users nostalgic pangs. They had to reclaim their hardware and as such prices went up and up and up!
Then we come to the dread crash of 2002-2003
Brought on because around this time most Amiga users got married!! The "crap" collected in a bachelors lifetime had to go! The deluge of Amiga gear on Ebay pushed prices down prices.
By 2005 saw prices steadily coming back. The Amiga users had their first children a year or two earlier and had an excuse to buy something "for the baby". Some bought lego, Scalextrics others Amiga computers so their kids could play the same games they did. The users who were too fat and ugly to get married now had high paid jobs in the IT industry which enabled them to get the dream Amiga they always wanted.
At the moment we are at the 2nd child point. This is where all the crap that was stored in the 3rd bedroom now has to go in the attic or the bin (aka Ebay). This is driving down prices as the market is saturated. Give it another two years and the Amiga community will be able to afford that 4 bed with study and the nostalgic call of the Amiga will once again push up prices.