I seen that myself the other day when I ordered my own 4GB kit for my 2.4GHz Alu iMac for just £39.09. Given the performance increase, or lack of depending on who you listen to, between DDR2 and DDR3 you've got to admit it's a hell of a lot of money for memory.
Those two memory chips cost over £200 than I paid for my iMac itself.