My advice would only buy what you need for a particular project (Make out a parts list and then find where you can get them the cheapest). There is no way to buy everything, and be prepared for every project. You'll just end up buying stuff you'll never use and run out of money for the things you really need. If you really want some general stuff, buy resistors/capacitors in common values, buy a nice soldering iron, a bread board and different colour hook up wire for protyping circuits, rechargeable batteries, i.e stuff you will use again and again.
David