For R2 builders, there used to be one main source who built the majority of the boards. Recently, the supplier has shut down production of the boards so he can begin outsourcing the entire process to China, which may take years to complete. Now there are very few unused boards left for new builders or builders with R2s who need new boards.
Fortunately, I have made my own board, which you can find in this blog: http://www.alexandraforsythe.com/blog/ps2-adruino-shield. Since the blog was written, I have created several more boards and I will begin manufacturing and selling them to other builders once I have finished the testing process.