Apple announced some new and updated gear recently and among those items were updated iMac AIO computers. There are many people out there who order machines with the minimum RAM available to save some money.
If you ordered your iMac this way OWC has announced that it now has RAM updates ready for the new iMac machines. You can get a single 2GB DIMM for $59.99, a pair of those 2GB DIMMs will cost you $117.99.
If that's not enough for you can also get a pair of 4GB DIMMS for $279.99 or four of those same DIMMs for $549.99. It should be cheaper to get your RAM this way than from Apple.