Additional packs outside of Question Pack 1 for GMATPrep Sof

You might already know this, but GMAC also publishes the GMAT Quantitative Review and GMAT Verbal Review books, neither of which overlap the OG at all. You could also consider purchasing the old GMAT Paper Tests from the mba.com website, but the questions are ancient, and there's a substantial amount of overlap with their other guides. It might be worthwhile if you're really scraping around for extra questions, though.

Another option is GMAT Focus, which gives you shortened (24 questions) adaptive quant tests, based entirely on retired official questions. I personally think that the price is awfully steep ($29.99 for one test... more than $1 per question!), but if you happen to have dollar bills shooting out of your fingertips, then it might be worthwhile.

You could also consider the ancient GMAT PowerPrep tests if you're truly desperate, but the algorithm is out of date, the software might do weird things to your computer, and the question bank heavily overlaps the GMATPrep exams. So I don't recommend PowerPrep for most people, but it's only fair to mention that it exists.

It's extremely difficult for test-prep companies to perfectly copy the style of the actual GMAT exam, so any "non-official" materials will inevitably have some imperfections, especially on the verbal side. If you need extra CR and RC questions, you might consider using retired LSAT materials--there are some cosmetic differences between the LSAT and GMAT questions, but the LSAT basically tests the same skills as GMAT CR and RC, and the language in the LSAT will really test your ability to focus.

I hope this helps, good luck with everything!