It has a huge backyard,and I can build another 900 sq ft 2 bedroom unit which I think will add $100k to the value of the property for a total of $300k.But there are no comparables, and my realtor could only give me duplexes which were only about $250k.My question is should I build this second unit rather than look for another "very hard to find now" flip?

If the tenant holds to the lease, you could have a serious situation on your hands.

I work in wholesaling/flipping houses in the urban core and have seen a handful of duplexes recently that are still off the market.

The trustee will usually be instructed to bid in on behalf of the lien holder the total of amount of the principal, interest owed, late fees and legal fees, as well as any other legitimate fees incurred by the lender.

Ironically, I was at a wedding this weekend and met a fellow who is licensed in Illinois and completed just a handful of transactions a year to supplement his income.  

That brings clarity to the situation at hand. 

I totally agree with you that anyone is traceable.

For now though, from what you've described, you'd just be biting the hand that feeds you and then chopping off your nose to spite your face. 

Monthly mortgage payment for 30 years with 4.5% interest rate is about $1,400 (total monthly). 

missouri or something buying $30k houses its totally different.