I have bought myself the technic set 9393 Tractor. I really like the model and I want to dig deeper into the Lego technic universe. I am not focused in building pre-designed models (although I enjoy it, and it would be a plus), but I want to have a decent set of technic parts, such that I can build models on my own. So what is the best way to get a basic set of bricks:
Buying some sets and take the parts from the sets? (rather buy a big set, or several small ones?)
Buying used parts as bulk?
Are there non-model technic sets, similar to the traditional Lego, for which they have door sets, wheels sets etc. ?
I know this question might be a bit broad. So let me add that I am not necessarily want to build motorized models right away. Also, I do not plan to build huge models, more in the size of the 9393 model.