There are numerous schools online and offline that can help you get started. Do a look up on the internet.
As a realtor, its your job to scour information and dig dig dig.
If you are actually referring to bank foreclosures rather than tax foreclosures, then the mortgage holder usually sets an asking price for 45 to 60 days and if they receive no offers will usually lower the price and hold it there for another 45 to 60 days. Hope this brief explanation was helpful.
Whoever the "seller" might be, they want to generate the best possible sale price, and the buyer wants to buy at the lowest possible price. The sale price is the price point at which the seller and buyer agree to sell and buy - a meeting of the minds.