For this price you need to go to the today only page and add it to your basket from there.
You can also get free delivery if you're a member of the avforums otherwise delivery is a hefty £6.99
The Corsair Twin2X4096-6400C5 G is a 4096MByte matched pair of DDR2 SDRAM DIMMs. This part delivers outstanding performance in the latest generation of dual-channel DDR2-based motherboards. It has been tested extensively in multiple DDR2 motherboards to ensure compatibility and performance at its rated speed. This Corsair memory has been verified to operate at 800MHz at the low latencies of 5-5-5-18. Corsairs line of 4GB memory kits are designed for PCs featuring 64-bit operating systems. Please note: Installing 4GB onto PCs with 32-bit operating systems is not advised since 32-bit operating systems do not support 4GB of system memory.