I actually save up my money from vending items to buy alchemy quests.. and we all know how expensive those can get. Then it's a matter of waiting around for Flynn to have one up for bid so I can get in on the auction action and get myself a new quest.
I'm actually in the middle of working on my second wing quest (and yeah, a lot of the items are really overpriced). I had to rest six months in between the quests just to get my cash supply back up.
I don't really desire a lot of items anymore. There are so many and I have most of the ones I really, really love, so dumping the money into quests or on items from people's wishlists seems like the appropriate thing to do with my money.