There was a thread on this website of this guy who had created a list of 200 SC qns from the Gmatprep. I am on my office computer, so when I get back to my home laptop, I will try to post it. In the meantime, you can try searching on the Verbal forum to find the thread.
The document is nothing special, except just a dump of all the SCs that are in the gmatprep. However, it is much better IMHO than the 1000SC documents. The 1000SC is essentially practicing quantity rather than quality, which are few and far in between. These 200 questions on the other hand all ALL top class. On my first attempt, I got about 1 in 10 wrong..about 20 overall in the document. I would research on all my mistakes and the second time I did the document, tha ratio was about 1 in 80!
Keep in mind though that the FIRST step should always be the Manhattan SC. Once you have the basics down you should go over this document to go over the more difficult questions.