Many states have laws about what an investor can and can't do when homeowners are behind on their payments and in the pre-foreclosure stage.
By the time a pre-foreclosure home is listed by the real estate agent the home would like be sold at market value. Banks must approve a short sale for a short sale to take place, and banks hire appraisers and other real estate agents to perform broker price opinions (BPOs), or estimated values of the home.
The goal would be to negotiate with the seller before the home becomes a short sale.
To find a pre-foreclosure home, buyers can search popular websites that pick up feeds from an aggregator or they can pay for the feed. Some foreclosure websites publish pre-foreclosures as well. If you have a lot of time, you can contact each of the homeowners to find out if any of them are interested in selling.
You can contact your county court to see how you can search for notices of default. These homeowners are probably not delinquent, although they might not be able to sell without doing a short sale as they might have no equity.
If you're buying a home in pre-foreclosure, keep in mind that you're buying it as-is. You'll need to cover inspections and repairs. It may take more time for the lender to approve of the sale.