Well, if you are going to come back to enter a field where job opportunites are scarcs, you'll need enough to live on for a couple of months, at least. If you can live with your parents and minimize expenses, that won't be too much money. And if you live in Dayton rather than Manhattan, that makes a difference, too.

If you are just starting out, why not look for a job teaching English in Japan for one of the companies that recruits in the US? You will still need a few thousand dollars to start out with, but you should be able to make enough money to live and have an interesting experience. And people who go to Korea seem to be able to save money.