For now you can get by without any crafting or gathering.
Most of the essential gear you need right now either drops from dungeons or can be obtained by farming tomestones (from those dungeons) and do not require any other gil than your repair costs.
I expect this to be no different when the Crystal tower comes out.

Once you get to the point where you start doing events like The Wanderer's palace and Amdapor keep dungeons the mobs in there will drop small amounts of gil which should cover for things like gear repairs and a bit of teleporting.

It is however always handy to have a better form of income at the ready for the times where you need to buy some higher priced items for quests (Like for your Relic weapon for example) and the best buyable accessoires when you reach level 50.
When you want to start doing higher tier content like the Binding Coil you may want to have a steadier form of income because your repair costs will go up and most groups will require you to use food.