That's what missions are for
. Run missions while questing and your quest rewards more than cover the cost of doing so (that is if you do not go overboard).
If you're wandering around, looking for nodes, you'll most likely engage lots of mobs. Killing them should suffice to cover the missions costs
I see the nodes as an "extra" to missions tbh, specially for lower grade mats, where the time to run them is small. What do you do ? Log every 5 minutes ? That gets old quickly. Staring at the screen is not so fun either.... So if I'm in need of those low level mats, I just do both things, spam missions and look for nodes at the appropiate planets