@Raj Pat
1) go look at the property before making an offer.
2) do not use Zillow to determine sales value. Use comparable sales that are in the condition your property will be in when you finish any rehabs thy have sold in the last 12 month.
3) go walk through listed/ available rental houses in the area and note prices
4) if the condition of the house is bad your lender might not lend on the property (no flooring, no AC, no appliances, old/damaged roof, termites or termite damage. This is the type of property that is the easiest to acquire be said it takes all cash or non traditional lending.
5) get experts to help you with rehab budgeting (or better yet get solid quotes from contractors initially)
I purchased my last property REO - purchased for $168k; $50k rehab budget; sale price $245k. I'm about 6 weeks from listing it. Purchased for cash and it took about 4 months of back and forth with the bank to get a contract.
I learned I suck at estimating rehabs (any specific project I was off as much as 30% in either direction). I was lucky I had as many “good-guys” as “bad-guys”. I also have a partner that used to own construction companies and help me scope work for subcontractors that reduced their risk and reducing my price. Also had some very creative solutions that took more time but saved thousands of dollars.
Always get 3 prices. The roof prices I got were from $7100-$12000 for the same scope of work. Don’t pay any contractor more than what it would cost for them to buy the materials (and better yet when they deliver the materials to the site).