Don't bother, just get a FS100.
The price of SD cards drops over time, while the price of internal memory stays the same. So you are essentially paying last year's prices for 16GB if you buy a FS11, while you pay today's prices for 16GB if you buy SD cards.
Besides, with SD card, all you have to do is plug the SD card into the computer - plug & play. Internal memory still needs cable, quite a pain.
If you want the SD cards even cheaper, go buy from amazon.com or any other reputable US online retailer. The price difference between US & Japan versus here is huge. Some use borderlinx, some use vpost, some tompang their friends to help them buy whenever they go to USA or Japan.
To save more, wait till this year's new models come out and then the prices of last year's models will drop. Should be around March or April, I'm not too sure.
Hope this helps you.