Your courthouse (city or county) will have those filed. You just go down there and ask a clerk (most are very helpful) how the system works. That's FREE.
Also, check your daily newspapers. Such notices (pending foreclosures and auctions) are required to have public notice. Assuming you already receive a daily newspaper, that's FREE.
As far as preforeclosures, if you're interested in short sales, many are listed on the MLS. It's just like a regular sale in most respects, except the lender must approve it. So, log onto your favorite Realtor's website and start looking. If you can do a keyword search, search for "lender approval" or "short sale." That's FREE.
Note: Very few foreclosures are tax foreclosures. (Maybe on late night infomercials, they are. But most real foreclosures are for non-payment of a mortgage.) Also, once a property has been foreclosed upon (your "repos"), then the lender owns it; it's too late to buy "before the mortgage holder gets it."
Now, there are tons of ways to find owners in preforeclosure, or owners who'd consider short sales, before they're on the MLS. But, those aren't FREE.
Hope that helps.