The PC Watch
website is listing pricing for the first DDR3 memory modules on sale. The modules are made by an to us unknown company called CFD and are available in 512MB and 1GB sizes. Both modules are rated at 1,066MHz, which is also known as PC3-8500. The memory chips used are made by Elpida and are labeled J5308BASE-AC-E.
The 512MB is selling for 21,900 Yen which is about €134, whereas the 1GB modules are selling for 43,400 Yen or about €266. Compared to prices of high-end DDR2 memory, this is quite steep, especially considering that you can't as yet get a motherboard to plug these modules into.
You can find a few pictures as well as some more information in Japanese here