I have bought off Hudson and Marshall, Williams and williams and auction.com
Auction.com has a lot of extra fees though and also advertises forclosures (to be sold at the courthouse and bought back by the bank) on their site as if it was a live auction which can be confusing.
I bought a flip house last year from a local auction company with only a sign in the front yard. Day of the auction there was a big snow and only like 3 bidders showed up.. that turned into a deal for me.
I got another great deal on a 3 bed 2 bath last year at an estate sale. The local auction company had only signs for advertising and posting on their website (no mls, facebook, zillow...nothing). I bought the place for 74k, put 10 percent down (at auction) and then the when I closed the bank appraised it at 130k and I gained a good piece of equity.
Within a couple weeks I had it rented for 1100 a month.
Moral of the story is to check your local real estate/ estate sale auction companies. Many do not advertise that great on social media, and you could get a deal.