I can get a Corsair XMS2 1024MB (512MB X 2) kit of DDR2 675Mhz 4-4-4-12 memory for US$99.50!! For comparison, the DDR2 800Mhz 5-5-5-15 kit costs $174.80.
As you can see, I can save a lot by buying 675Mhz memory. My question still remains: will this slower memory hinder my capacity to overclock the E6300? It seems an overclock to 2.6Ghz is enough to outperform most pre-Conroe CPUs.