I'm worried about money too. I'll be going to an in-state school either way, but in California, the cost of living is really high, so I'll still be looking at borrowing a good chunk of money. I'm also neither epi nor bio-stats, but rather more health promotion.
From what I understand, the MPH is a very marketable degree regardless of speciality (though epi/bio-stats do get paid more!). We have an impending lack of health professionals in this country so you should be able to get a job.
Another thought - if you are considering a private school, they may have more funding opportunities available to you than a public one. There are probably more privately endowed scholarships / fellowships and their TA / RA positions probably pay more.
I have a few more weeks to decide whether or not go back...