Wear 15-20K of gear to make money and remain competitive.
Start wearing 25-30K to have a good chance of success on the battle field once you have a cash stockpile of about 25-30K in reserve.
Wear up to 40K for your "nice stuff" if you don't care about making all that much money, and understand that "tilting" will happen in drastic ways, and thus you should have a cash reserve of 30-50K to make up for bad days.
Understand that with an average multiplier for an average player, anything past 46K in gear will likely lose you money not just short term but also long term.
Oh, and pre-emptive before people usually start babbling about how much gear they use:
1.) I said average player with average multiplier.
2.) Your Heirlooms factor into your equip cost and not how much you pay for upkeep.
3.) Arrows have different upkeep rates then other stuff.