A property in "notice of default" status still belongs to the purchaser/owner - but it's getting dangerously close to foreclosure. If the house is foreclosed upon, then it will be sold at auction to the highest bidder. Most of the time, the highest bidder is the lender who's owed the debt that caused the foreclosure in the first place - but not necessarily.
If the lender takes the house at the auction, then they will try to sell the house - that's an "REO".
So - pre-foreclosure, you negotiate with the previous owner and maybe their lender. Post-foreclosure, you negotiate with the new owner, who will likely be the lender.
Realistically, you can probably offer the lender a fair amount under comparable homes in the neighborhood - not a ridiculous amount, the people on the other side of the transaction aren't idiots and they're not going to sell a $500K asset for $50K. On the other hand, the bank doesn't want to own a bunch of vacant houses, nor become a landlord and rent those vacant houses to tenants. The bank wants to get rid of the houses and concentrate on the banking business.
Selecting a reasonable offer is going to involve analyzing both the prices of comparable houses, and the trends in the market, as well as for this particular property. If the bank has been sitting on a vacant house for 270 days, they're a lot more motivated to make a deal than if they just foreclosed last week. If the property in question is the only property for sale in the area, they're not as likely to make a deal versus the situation where half of the houses on the street are REO's that have been on the market for > 180 days, with declining prices and no serious offers.
The advantage to buying a home that's been foreclosed or is threatened with foreclosure is that you can get the property at a discount. On the other hand, you're walking into an unpleasant situation, and the property won't have enjoyed careful maintenance and cleaning before you move in.
That means the owner will be facing the forclosure process to start soon if he or she doesn't try to bring the mortgage up to current. The short sale will take place if he or she will try to sell the property to pay back the loan. If the seller's financial statusis qualified for short sale (that means he or she has no asset except the house in foreclosure) then the lender might consider to accept the offer once it is submitted to them. based on the loan the sellers owed. The amount of the loan had to paid plus the cost of process paper for forclosures such and such. Bank owned properties will be sold close to market price not shortsale properties. You can request more information in details on my website.