I can sell a $3000 iMac for $2000 two years down the track; making the upgrade "cost" $1000. It'd cost me roughly the same to buy a GTX 770 (AUD$500), a new i7 Haswell and a 128GB SSD, which are effectively the major upgrades between my 2011 iMac and the (predicted specifications) of the 2013 refresh. And then I have to hope that someone else has tested those parts before I have!