I'm not sure if there are promotional codes for the Kaplan Qbank, but if you join AMA you can get like 30% off the Qbank. I think you can sign up for a year of AMA for $10 or something like that, so you'd net save $50.
You mean for AMA membership? Not sure on that one. I wouldn't recommend sharing 1 Qbank subscription between two people because then you can't track your own progress separately from your wife's progress.