We're not gonna lie to you -
The latest iMacs (mostly the 27 inch iMacs) have been having a few problems with capacitors and screen flickers.
Although this isn't exactly a good thing, it is going to be fixed soon - users from the official Apple forums have already begun to report that their Macs are finally beginning to function smoothly.
So just wait a few months, save up some more money to get one - they won't have this problem for much longer.
SSD~