I dont think I sold a single item to npc or on mb until I was lvl 50 (only sold a few things recently cause armory and retainers full). Not once was I close to running out of gil. My armor came from quests or occassionally cheap crap from npc. Gear was mostly irrelevant until higher levels. I spent gil on TP, but easily made pleanty from quests and later leves. Whether an NPC gives 1 gil or 50 gil for useless armor seems irrelevant.