It's not as simple as comparing a price in 1990 to one today when deciding if the hardware is more expensive. You have to consider depreciation and the prices of the Amiga contemporaries, today. It's a comparative thing. In 1990 a new PC would cost around $2500. An Amiga 4000 cost around $2400. Today you couldn't give away that 1990 PC, yet the Amiga 4000 will still sell for $1000. This is what people are referring to when they say Amiga equipment is expensive. When they say 'Damn Amiga stuff is expensive' what they mean is, damn this stuff has not depreciated the way you'd expect old computer equipment to.
In some cases the equipment is worth more now than when it was new. A Blizzard 603e Power Board w/ 120 MHz 603e cost $399.00USD in 1997. Today you'd be lucky to get one for less than twice that price. I've seen them sell for over 1k$. Toastscan Scandoubler Flicker Fixer. Originally $159 retail. The last one I saw sell, went for $910.
These are the pieces of equipment people are referring to. Not just some $10 Amiga 500 you can get at a flea market. So I would say some things are cheaper. like the Computers themselves, but some things are much more expensive, such as Amiga expansions.