iPhone was definitely a team effort, so fortunately I had access to the top engineers at Apple to guide my personal development. The difficulty wasn't really learning the material itself, but rather figuring out what was worth learning. As for equipment, there's workplaces like Hacker Dojo that have community resources, and in a pinch you can rent equipment from places like MetricTest. Oscilloscopes are pretty reasonable, but it's mainly the RF equipment that gets into BMW price territory.