Here is another idea for you to make more money. People love rebates and sales. You already do gold sales but why not look at something along the lines of a rebate. It doesn't have to be a big rebate but I think it might initiate some additional gold expenditures (knowing one might get a little back).
LTQ Normal Mode completion: Unit Prize +25 Gold
LTQ Prestige Mode completion: Unit Prize +200 Gold
Boss events:
Tier 1, 50th Boss: Unit Prize + 5 Gold
Tier 2, 50th Boss: Unit Prize + 15 Gold
Tier 3, 50th Boss: Unit Prize + 25 Gold
Tier 4, 50th Boss: Unit Prize + 100 Gold
Tier 5, 50th Boss: Unit Prize + 200 Gold
Courtesy of the Evil Mastermind