newegg.com offers the Corsair XMS2 4GB PC2-6400 DDR2-800 240-Pin Dual Channel Desktop RAM Kit with two 2GB DIMMs, model no. TWIN2X4096-6400C5C, for $89.99 with free shipping. This $25 mail-in rebate knocks it to $64.99. That's the lowest total price we could find by $15. This RAM features 5-5-5-18 timings. Rebate ends November 30.