The edition you have specified must not be accurate.

There is an official guide edition 10, 11, 12
There is also a verbal and quant expansion guide edition 1, 2

I think you have:
(1) OG12
(2) V2
(3) Q2
These are the most recent guides published as of 4/6/2011

If you want new, different problems, you want an official guide that is as far away from those editions as possible.

Why?

The OGs recycle about 2/3 of the content per edition.

Other great sources of problems that I would go to BEFORE buying an old OG on ebay:
GMATPrep (It's technically a test, but you can keep taking it over and over to get new, real gmat problems.)
ManhattanGMAT (Tons of practice tests with GMAT-like problems.)
800Score.com (Tons of question banks and practice tests with GMAT-like problems.)

-Tom Rose
www.TheMBAShow.com

Full Disclosure: I work for ManhattanGMAT

Hey bkw,

One other new source of official questions - if you "like" The Official GMAT on Facebook you'll get access to some exclusive questions released for that purpose by GMAC: https://www.facebook.com/OfficialGMAT

This is a new feature from GMAC launched just last week, and should be another helpful resource. At www.mba.com you can find some other official resources, as well.