I believe that planning succeeds better than just ESP. If you need parts, you always need to have at least two suppliers for each part and hopefully three or more. Why? Just for the reasons you stated. In a crunch, you need options. If you have a sorted list of suppliers, you can quickly find a replacement source for a while if your primary source experiences unexpected difficulties.
It is all about good risk management and planning.
Just my opinion.
The Other Tesla David Blaza5 comments I find myself going to Kickstarter and Indiegogo on a regular basis these days because they have become real innovation marketplaces. As far as I'm concerned, this is where a lot of cool ...