I'm looking for advice on whether I should purchase my father-in-law's 6 unit apartment in Burien, WA (10 minutes south of Seattle) as my first deal, or perhaps help find him a seller that would pay more than I could and is a couple years ahead of me in REI. 

To get a deal, you have to find a problem to solve.

I'd like to invest more in that area, but it's much more expensive and harder to find deals.  

USDA offers 100% financing if you can find a property that qualifies for USDA.

Search for properties in your area as if you wanted to find a place like yours.

Find someone in the neighborhood of your building to help you out.

I've looked through the forums and can't find answers to a question similar to mine so I thought I'd post.

With a budget of $300K-$400K, you could potentially find single-family homes or small multi-units in those areas.I'd recommend researching rental demand near universities like Duke or NC State or even checking out neighborhoods with strong job growth near tech hubs.

I fairly positive that wont work, i have read that contacting mortgage brokers is the best way to go if you can find one.

You need to find a zip code where land values are 10% of less of after built value.