Your statement of 2-5k in repairs per run, per dungeon, is blatant misinformation. 500 gil would be more accurate assuming, say, one wipe and blue gear.

That said, you're quite right. As of now the currently that is provided by the game in the form of dungeon rewards on the way to 50 seems to be the VAST majority of cash that'll be changing hands, with only a small new trickle coming in.