I was looking today on one website and found over 400 houses under 100k.

Account Closed I think you can find these data points on the apartments.com site.

I found Roofstock.com to be very helpful in determining rent value, expenses, current tenant history, and management options but I was wondering if successful investors actually use this website.

Thanks for the suggestion I've never heard of this site.

I suspect barcolounger went right over the kids on this sites head.. just like my rolodex.. which I still use.

I've now had my license for two weeks, joined Keller Williams, and am struggling to get in enough time blocks outside my current marketing work/family responsibilities just to set up my real estate agent systems (MLS, CRM, training, website, social media, etc.) 

Its on page 7257 (the third page of the linked PDF)https://www.hud.gov/sites/documents/DOC_35681.PDF

It is going to need at least 15k of fill dirt in site preparation and the cost of the structure would be around $250k.

It is going to need at least 15k of fill dirt in site preparation and the cost of the structure would be around $250k.

Very cost-effective option and shows up on all of the major websites (Redfin, Zillow, etc.).