The military has the best equipment, so I recommend buying military surplus to outfit your ship. Go to Perry Naval base to pick up the best scanners and weapons.
I actually found no need to buy maps at the software booth. When taking missions, the nav course is programmed in to your computer, so it tells you what jumps to take at each step of the journey, even though I didn't buy the maps, the jump points were all labeled anyway, so I could easily find my way. As I went to each system, the ship's computer built the map for me.
Just take lots of cargo missions to various different systems and you'll eventually map out all of the important systems.
--Brandon Young