Since most foreclosures do end up being listed by a broker, consider working with an agent of your own who can provide any necessary information; if purchasing with a mortgage, be aware that a mortgage pre-approval letter is required in order to determine your price range and for any offers to be taken seriously.
Contact a local Realtor who has access to your local MLS. The MLS will have all available properties, including foreclosures and HUD homes. Don't fall for people or companies trying to sell you a "list of foreclosures". They will ALL be in the MLS.