I think playing therapist though is the right strategy but sounds like you might have to pay more than 49k to get Frank to "sweat" by saying no.

.$50k spread over three 401k accounts.Excellent credit.FHA loan on your primary (and only) house in Washington DC, with $200k in equity.The goal is to generate an additional $1,500 post-tax income by the end of 6 months.Thanks so much for playing!

Doesn't the general economy/market timing play into it?

How should the numbers play out in a duplex and what would be a good offer price to make deal worth while?

I've driven through it and a lot of kids are outside playing and riding bikes it seems like a great place for families to live which is why I want to buy in this area.

My thought is to proceed with the duplexes for a long term play.

Its a long term play as you can have both elements of cash flow and appreciation. 

You can play the waiting game and break even on rent or get enough appreciation shortly to offset the depreciation recapture.Or your mom (under your direction) could do a 1031 exchange and sell this property using the proceeds to buy a similar priced property maybe closer to you or one that cash flows better.  

If it is one thread the people posting can play off others' information and get deeper discussion.

If you play your cards right, 4 years could give you a smooth transition from The Marine Corps to real estate, assuming you hit it hard for the next four years.