You can get through the entire story without having to stop and earn gil. Just sell all of the junk you get. Pick up side quests that offer gear. The MSQ gil rewards will end up paying for all of your teleporting needs. Basically the gil in this game is mainly for indulging in any side content (crafting, housing, etc.). There are multiple ways to earn battle gear that doesn't involve gil at all. But I think the devs did a pretty good job of making sure you have plenty of gil to carry you through the story. Side quests can always give you a little more.