I just bought one of these (an interesting story unto itself).
Over on HardForums I saw a thread saying that a Hitachi USB external drive, Model H2200U, used the 7K200 drive instead of the advertised 5400rpm drive. A bunch of people bought them, and found that if the serial number on the box started with DTG, then it was the 7200rpm drive.
The price a few weeks ago was $139.99 for this external drive, last night I hopped on and bought it (picked up in store) for $149.99, and today they are $169.99.
http://www.bestbuy.com/site/olspage.jsp?skuId=8355709&type=product&id=1177112455216
I dropped it on as a USB drive, and it was the 7K200. So I used SuperDuper to back up the hard drive, and today I swapped it into my MBP SR 15.4. It's a fantastic drive, very quiet. Haven't benchmarked it yet.
Go to hardforum and search on 7K200, the thread is one of the top thread hits for that (Hitachi 7200 200GB Notebook drive plus case....)
I used a 10% off coupon, so with tax it was still under $150, a GREAT deal as long as you are willing to be patient and cautious with the hard drive swap if it's for an MBP.
Since you need to look at the serial number, I suggest that you do not buy online, but rather go into the store and get one with the right serial.