Over the course of the game, you'll acquire several junk items from the battles you participate in that are worth a few cents at least. This will build up over time. The only use for these is
vendor fodder, or to simply sell them. This is only one of two ways to quickly accrue a lot of cash (as near the end of the game, stuff becomes more expensive than you might prefer it).
Do note, if you sell ANYTHING, you will end up missing out on: