First, how is it priced? If it is priced above market value per comps, then the sellers have more room for negotiations for less
Second. How motivated is the seller? If he needs to sell in a hurry, then the seller may be more willing to accept a lower price
Third. If the seller still owes money, how much will it take to pay off the loan(s). Will he have enough to pay off the loans and closing costs? Is it a regular sale or short sale?
Fourth: Who is the seller? If it's a bank, you or your realtor may want to research how much the bank foreclosed on, and negotiate from there.
Remember that even if a property is a short sale or foreclosure, they won't give it away. Take a very close look at market values, the seller's motivation for selling...and negotiate from there.
Every market is different. It all depends on the location of the properties. There is no set range that you could request. As the other agents have indicated, it depends also on how motivated the owner is and if it's overpriced. A good market analysis should give you a better idea on how much the house would be worth. Work with an agent, which will not cost you anything and we will give you a CMA. Feel free to contact me if you have further questions.
Sellers will not automatically accept a lower, or much ,lower price just because the offer is all cash. They still have to be comfortalbe with the offer. You may have an advantage over a competing, similar offer, but don't assume a seller will drop their price by any large amount just because you don't have a mortgage contingency.
This answer will vary greatly from seller to seller - it also depends on how well the home is priced in the first place. An overpriced home may sell for 20% below list price, simply because it was hugely oveprriced in the first place.
Final sale price has to do with time on market, demand for the home (and condition), motivation of the sellers and competitve list price.
All cash offers are an iincentive, but don't mean a large automatic drop in price.