@Eric Blackford
I am by far not and expert. I just started out last fall. But this is what I would do:
1.) Look at comps for the duplexes in your area. If there are none, then comps in similar size towns near you.
2.) The owner is an out of state owner and is probably just trying to get out. The amount he'll take is based on his motivation. You should probably even supply a personal letter with your offer indicating you're trying to make a better place to live in your town, you're local so the tenants have a close by owner, etc.
3.) Your financing is OK. If you push it to a 30 year term, you'll get more cash flow...slightly.
4.) What seems to hurt you on the expenses are your $1200 utilities and $840 insurance. Our insurance on a $55K duplex in SC is 499 and we have no utilities.
If you could get it for $55K and get your rents up to $540/month, you're looking at a good 20% CoC.
You'll need to decide what your goals are. My personal goal is 15% CoC.