Don't worry. You don't need to show financial evidence to sponsor your wife.
I was a student in CU two years ago when I sponsored my wife. I called the CIC hotline, the person at the other end of phone said there is no finanical requirements to sponsor your wife. Couple reunion is the first priority among all the other cases.
Just send all the needed documentations and then wait. It shouldn't be very long ( in my case, it was 4 months.)