A couple of years later, a less expensive solution is to get the Sintech PA6007 1.8" ZIF/IDE to mSATA adapter and mount a standard mSATA SSD on it.
The Sintech adapter is about $15 on Ebay, $20 on Amazon, and I've seen it as low as $10 around the web. The interfaces are all proper, but I'm not sure if there are power demand issues.
240GB mSATA SSDs have been turning up at Holiday sales this year (2013) as low as $130 -- mainly at Amazon and Newegg.
So for under $150 one can get 240 GB of storage.
Of course, just before the Toshiba MK2431 was discontinued, one could get 240 GB of much slower storage for ~ $75.