Well, I think my company's tests are pretty good
You may see some question repeats on GMATPrep - I don't know the actual probability, but there are likely to be a few, unless your scoring level has changed a LOT since you took the first two tests.
You can also try to see if you can get your hands on the old PowerPrep software (the prior version of GMATPrep). Not quite as good as GMATPrep but better than the old paper versions.
In fact, any reputable private company's CAT tests (us, TPR, Kaplan) will be better than the old paper versions. I'm pretty sure you can sign up to take one of ours for free (we used to do this and I don't know why we'd stop, but you'll have to check and see), and I'm sure at least one or both of the other companies do this too as a marketing thing, so that can give you another test or two for the next week.
Don't do too many tests in the next week, though - that's like running a practice marathon every day the week before you run a real marathon. You'll burn yourself out.
