You know Steve Jobs never in all his time at Apple announced a new iMac at WWDC, don't you?
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If you buy today, you're still paying full price for something that's over a year old. And given that Apple computers aren't exactly the cheapest to begin with....
I bought a second-hand iMac, i7 3.4Ghz, 16GB ram, 2GB GPU, 27", 256GB SSD & 1TB HDD, a month or two ago. Been super pleased thus far with its performance.
Get a refurb, buy it cheaper, or get it second-hand. I kind of knew I'd be saving myself unnecessary angst if I didn't play the waiting game.
A really good iMac now is better than no iMac at all IMO.