You're probably seeing a SCAM ad, on Craigslist.
Scammers from Nigeria often copy existing legitimate listings, including photos from the MLS, and then price them considerably lower than the real listing.
This usually happen only with leases, and with vacant properties.
OR, you're seeing a pre-foreclosure listing, which only includes one of the loans on the property.
If THAT's the case, you might be able to buy the property as a short sale, but it probably won't sell as low as the price you've seen - that may just be a teaser.
Lastly, if it's a real foreclosure ad, you would have to show up at the property auction, and be prepared to pay cash, against 5 to 15 other bidders, who are experts at that sort of thing.
In ALL the scenarios above, you're either going to lose some money to scammers, OR, end up paying a lot more than the list price you're seeing.