First, let me congratulate all you iMac owners. When I started shopping for an used iMac for my 5-year old I was stunned to see how much 3-4 year old iMacs have retained their values! These things are not cheap, and they are 4 generations old (about to be 5)! I'd like to spend no more than $600, but I'd like it to be a 8,1 or 9,1 model if possible for no reason other than it's not too old. I want this computer to last 5 years or so, and components can fail after a time. The smallest sized screen and slowest processor would be fine, though. Any suggestions? I might have a line on 9,1 20" educational iMac for $600. Would that be a good deal, given list was $899 in 2009 and it's not as upgradeable as the other iMacs? TIA!