Ooooh, I like that Sage, especially as a move to be made before carouse! Really? It'll cost that much to throw a good party? Oh bugger, now it definitely has strings attached too? What does that mean when I befriend a useful NPC?!
As some of you know, we dabbled around with this concept when DW first emerged from Apoc D&D, and I found that the abstracted 'Wealth' stat was ok in implementation. But it sort of worked better as an abstraction of the barter economy of AW. I thought it needed a more 'resources' type feel (as in Burning Wheel), where fluid gold and gems is more of a liquid asset, whereas 'wealth' was more a measure of the adventurer's total resource potential: domicile and safe storage, retainers, magical miscellany, favours from friends in high places, that sort of thing.
I guess it depends on how much of a fiscal game your group wants to play. Currently in our long running game we still have a 'wealth' stat that is capped at +5 (though no one has got there yet) which represents their overall ability to manage their 'money'.
Unless there has been an issue recovering loots in the dungeon (we still use the loot move - so cool), its assumed the takings from the adventure allow a carouse style party, or the players can increase their Wealth by 1. They generally choose to Carouse if only for the adventure hooks they can sunsequently author. Though the one time they stole a dragon's hoard I allowed them both the Carouse and the Wealth +1 :)
If they want to buy something and its worth a roll (its fictionally worth making a move over) We have a move taken straight from the Apoc D&D ruleset. Generally a 7-9 is a hard bargain, either lose one Wealth or have strings very much attached. A miss is usually both!
I target their Wealth stat rarely through GM moves, but sometimes its just the ugly choice or consequence the story needs.
That said, when playing a one-shot, I use the gold as listed and it works fine too :)