Dire Maul takes roughly an hour and a half per wing while Scholomance and Stratholme take about two hours
. UBRS provides a wealth of loot as well and takes a variable amount of time. If you aren't level sixty and want some good battleground items, don't worry! You can run instances you've already completed to get loot drops. You may not get the quest XP/gold but you'll get the elite enemy XP and plenty of additional blue items. With that in mind, the best idea to make WoW money is just not spend it! You should only spend money on things you need badly, like repairs and skills.