There is no financial minimum you need to make. You just need prove that yourself and family will be supported without using social assistance.
For example, myself, at the time of submitting the application to sponsor my husband, I had very little in my bank account, as Id just worked three years in a developing country making a local wage, had just moved back to Canada and was unemployed. To prove my husband would be supported I showed schools boards Id applied to (I'm a teacher), I showed my degrees to prove I had the earning potential, and I had a letter from my parents saying that we could live with them so we could save money and get on our feet. I was approved to sponsor with no problem.