We checked the prices of the memory and we found out you can buy 2GB of MDT PC2-6400U CL5 (DDR2-800) for €100.
We only took into account the memory that is available or will be available within 24 hours. You can walk in and get yourself 4GB of this memory for €99.98.
You won’t get the fastest timing but this is the best ride for the money. You can buy it here.