Sometimes the best way to store money for yourself is actually to at the end of the day before you buy anything is to send about 10% of what you earned that day over to another account. And you only get money from that account when you have a really big purchase.
As for your quest, Ive got my eyes on another nightmare as well.
Look into the marketplace, since there are 11 generations of the nightmare, you should look to see if there are any that are worth less gold.
http://www.tektek.org/gaia/price/8719/The_Nightmare_11th_Gen.newer generations are usually cheaper, but not always, when you think you might have enough, remember to check, or if you're even quite close, you might be surprised and get a good deal.
