It realy depends on how far you want to get into making knives and what techniques you want to use. There is a great book for getting started by Wayne Goddard called the $50 knife shop.
In the book he explanes how he went to garage sales and picked up different tools and how he repurposed some items around the house to set a basic workshop up. It has a section in it where he talks about tribal knives and how they are made in places that dont have electricity or power tools. I would say the minimum tool set up would be a grinder or file, drill and a vise. You would not be able to forge your own blades or heat treat with this set up but you could find hardened steel and cut your blades out with a grinder. Saw blades, lawnmower blades and files are great metal sources for this type of knife making.