That's from Crucial/Micron who are expensive... Try searching ebay for the identical parts?
I'll do my best Tony going to paste the Ram specifications here so don't have to run the scanner again will try ebay one more time
Crucial 8GB Kit (2 x 4GB) DDR2-666 UDIMM
CT1004220
• Brand: Crucial
• Form Factor: UDIMM
• Total Capacity: 8GB Kit (2 x 4GB)
• Warranty: Limited Lifetime
• Specs: DDR2 PC2-5300 • CL=5 • Unbuffered • NON-ECC • DDR2-667 • 1.8V • 512Meg x 64 •
• Series: Crucial
upgrade for ASUS P5QPL-AM system