She doesn't need to meet a minimum income to sponsor you, true, but you will need to show how you plan to support yourselves. A PR can be denied if it appears that no other arrangements have been made for their care than relying on welfare and CIC is not convinced he/she is willing/able to support themselves.
So. Gather all the evidence you have of savings, yours and hers. And make sure you show any professional or other qualifications you have that are transferable to the job market in Canada. If she is job hunting, she can show evidence of that too. If you are sending her funds, make sure you document it. Make a strong case for your ability to support yourself and her when granted PR.
My husband is on disability, and works at his trade (construction) when his health and the weather permit, so his earned income is sporadic at best. So when we applied, we included evidence of his savings and investments, and copies of all of my professional qualifications (accountant) and school records for high school showing I am fully capable of supporting myself and integrating into the Canadian workforce.
Basically I am self employed. I work with my father and will continue to do computer based work after I move to Canada, and will continue to draw a salary while I look for a job here. I have 2 potential interviews lined up but I don't want to schedule them until my paperwork is further along.
I already support my wife in Canada, we have an apartment there which I am paying for. My wife is not able to work. We have a joint account and I travel back and forth to Canada often... every 45 days at least. In the US we own a home, which is paid off with no mortgage(should I list that as an asset?). Is the fact that I already have a place in Canada(and have had it for 7 months) proof that I will be stable, since my income will not immediately change after moving?