I was talking to the bank, and they have two options.

Juan Ayala you can try US bank but they’re not local to Texas.

Get an actual interest rate from a bank - for investing, it'll probably be around 5.5% (depends on your credit).Don't purchase based solely on the 50% rule (I've said it several times, but once more won't hurt).

Using your own money or using the bank money?

Shop around to your local credit unions and small banks.

What's the most efficient way for me to accomplish this.  1st bank I talked to said they would do 75% LTV because it was an investment, then came back and said only 70% because it was a duplex, that was at 5.75%. 

I can probably put down up to $20k, but I like having a little more liquid assets in the bank since almost every time I've received orders to move, I've had less than a month's notice and there are quite a bit of expenses in moving...However, since I'm "guaranteed" to be in NY for two years, I think I can afford to keep less money in my checking/savings accounts and put down a large down payment. 

(Arrives in your bank within 72 hours).

I work part time right now as a bank teller and I don’t have much money saved up. 

There are arguments that they are not backed by anything or that digital monies are insecure, but your fiat money in the bank is stored electronically and backed by nothing but a promise.