If the numbers work and you can get the deal done, it's probably not a bad deal.One thing to remember when dealing with time capsules - an enormous amount of building codes have been adopted since the 60's, so you would do well to get a good GC that works on old stuff to come and do a walkthrough before you get too far.  

Slim pickings during the winter time

With that out of the way, I think that <$100 total cash flow for a duplex is a little bit to slim of a margin.

Slim.

The chances are so slim, why worry about them.

However, it occurred to me that once you reach a certain number of properties then the standard amounts don't apply. ( 3-10% vacancy, 5-15% repairs Etc ) For instance if we own 10 properties then the chances that all of them will be vacant at the same time would be slim.

@Aaron Taylor Because of the slim margins, I figured I could buy Subject to the loan and sell on a lease option.

If agent fees are off ( I would think they would be 40k to 60k) deal gets real slim real fast.

Some flippers are doing close to that on sub 200k houses, so I can't imagine there would be much incentive for them to take on a 500k project with that slim of a profit margin.  

If it's $10K, you're still wasting your time because the likelihood of recovery is slim.