We need a lot more information to help you with this.
How bad is the rust? Some people would call a 2" hole "major" rust, while others see the entire floor pan rusted out as a minor issue. Be as specific as you can. How much area is involved, what specific areas or structures are rusted, and how bad is the rust--from light surface rust to entirely rotten.
Also what is your skill level?
And what facilities are available to you? You could have all the skill in the world, but if your reapir facility is a parking space along the curb, you can't do much.