I think you'll find this interview invaluable: https://carrot.com/blog/negoti...

Extra points for community redevelopment.Ultimately though, don't sweat too much about the data.

I did start a spread sheet to track where I've sent letters, how much I've offered and pulled some data from Zillow and Redfine so when I do get a deal I can see how valid their estimates are.

They have a data base where you can purchase liens/deeds through their relationships with banks and hedge funds. 

Assume the house is valued at 1,100,000  and the FMV and AVR are close in value, and you live in California; The taxes would eat up a lot of the value of the prize, unless.....?

@Brian Walters I use Propstream to get my data! 

There’s an additional cost there, but if I was you, I’d consider fronting that cost in advance so you have strong data to evaluate your potential investment properties with.3.)

Based on the market and the improvements I would bet the property has increased significantly in value. 

What data points are your lenders expecting?

Any scarce item has greater likelihood of increasing more in value over time.