No, SSD isn't expensive. In fact, it's way affordable, as of today, even with Apple pricing. Just some numbers, from a SSD supplier on Europe:
128 GB SSD Samsung -> 110 euro
256 GB SSD Samsung -> 200 euro
512 GB SSD OCZ Vertex4 -> 420 euro
(there're also very interesting prices for models in the 300GB range but I cannot find them now)
Add about 100 euro to those prices, and you'd get what Apple would ask you for such products:
128 GB SSD -> about 210 euro
256 GB SSD -> about 300 euro
512 GB SSD -> about 520 euro
Please enlighten me in what way such prices are expensive.
I don't know what Apple will charge, but a 3TB HDD can be easily had for $200 USD. I don't think you're getting one in SSD for under $2000 any time soon.
I think his point is why simply one or the other. Which is a problem that many of us are coming back to with the iMac. Although the new design is sexy, it does sacrifice the ability to upgrade RAM on the 21.5 in model and it removed the ODD (not a problem for me, but some are upset about that). And why simply 1tb, or 3tb, or a 1tb fusion or 3tb fusion or 768gb of flash (which is going to be REALLY pricey.
Personally, I would prefer a 256 straight SSD drive, but I am also happy with the Fusion. I would also like to buy as little RAM as possible from Apple and then pay ~$200 less to upgrade it from somewhere else. *Note: I don't have the space for a 27in in my apartment #NYProblems
It might just be the 21" iMac users are generally not the kind that are power users. Non-power users generally don't need a lot of memory. There will always be exceptions, but Apple only chases down the exceptions so far if they have other objectives.
I wouldn't be surprised if the memory is just harder to get to rather than impossible to upgrade. I'm interested in seeing the tear-downs to see what they really are like inside to know for sure.