Flash memory might not be that bad of an idea. Most flash drives these days have an abstraction layer between the drive's blocks and OS to distribute writes across the device to keep from hitting the write limit inherent in any single block.
eg, if a drive is formatted with FAT, the allocation tables will be written to many more times than most of the rest of the device. Without this abstraction, the portion of the memory holding the FAT table would die very quickly, which is very much not good for obvious reasons.
Depending on how busy your site is, flash memory could work quite nicely. How long will it take for you to completely fill the drive 10,000 times?