The prices of Amiga's go up and down in value quite a lot.
To give you a history:
1994 : Amiga's at the height of their prices
1996 : Amiga's at the all time lowest of their prices, everyone trying to sell to buy a PC
1998 : Amiga's continue to fetch low prices, made worse by the introduction of GOOD emulation on the PC.
2001 : Prices start to go up, especially on high-end items such as accelerators. Reason: Remaining Amiga users now have left school/university have good paid jobs and free cash. Ebay has had some affect on price.
2003 : Nostalgia and Retrogaming become popular, those that sold their Amiga's in 1996 all want to buy them back, prices continue to go up.
2007 : Amiga's back almost to their all time highest, bidding fever on ebay coupled with the now high salaries (£20k-40k) of the top end Amiga owners have made £100 affordable. PPC, 060, GFX cards now in great demand.
2010 : Amiga owners get married, computer junk no longer acceptable in the house, prices start to go down as the supply of Amiga's on Ebay outstrips demand.
2012 : Most Amiga owners now feeling the pinch of having 3 kids and a mortgage as interest rates spiral. Everything computer like not essential must be sold to pay the mortgage and university fee's! Prices of Amiga's hit rock bottom.