1) pending delete auctions.  These are domains that were not renewed and are going through a pretty complicated drop process.  You can backorder these names at the auction venues and then each attempts to "catch" the dropping domain.  If one is successful you win the domain at $59 if you're the only one to backorder the name.  If more than one person backordered the domain a 3 day private auction is held.  Once the domain goes through the drop process, the back links have pretty much zero SEO benifit to the new domain owner.
Sometimes people purchase domains that they plan to build a website on or sell in the future, but it just doesn’t end up happening. If an individual decides that it is no longer worth the yearly investment of keeping the domain in their account, they may choose to let it expire. Or, someone might just forget to renew the domain before the expiration date. If this happens, it’s a great chance for other domain investors to score rare domain names that are pending delete. Spending time perusing the list of recently dropped domains can be a worthwhile way to find high quality domains.
Today, the story is different. Domain name registrars realized that they could auction expired domain names to the highest bidder and generate additional revenue. If no one wanted the domain names in an auction, the domains would then drop and become available for anyone to register. Much of the time, however, domain names are successfully auctioned.

* “Thousands of domain names that reach expired status never make it to any auction service and are released by the registry.” I think this is only if the registrar a) has an auction partner and b) nobody places a bid at the auction house. In that case, it drops normally and is deleted from the registry and available for anyone to hand register — including backorder services like SnapNames.com or Pool.com. I’m not sure why a registrar wouldn’t list an expiring domain name at the auction house as it could lead to extra revenue for them. Can you, Jamie?

The database also gives us the chance to analyse Whois, IP, NS, MX records and website content of every domain and to offer unique investigation and brand monitoring services for which websites like Whois.Domaintools.com charge a lot of money. With the tools we have developed we can offer Reverse IP, Whois investigation and B2B research in bulk at a world class quality/price ratio.

Now the numbers of errors, for we give up crawling a web site in case you know, they've got some kind of anti scraping technology or the web sites just completely knackered or something thirty is generally fine. Limit number of pages crawled per website most the time you want that ticked. I have it about a hundred thousand less you are going to be crawling some particularly big websites. I like that there, because, if you have an endless, crawl and there's some kind of weird URL structure on a website like an old-school date picker or something you don't want to be endlessly stuck on that website. Show your URLs being crawled. Now, if you just want to see what it's doing, you can have it on for debugging sometimes, but I generally leave it off because it makes it slightly faster and writes results into a text file so as it goes along and it finds expired domains as well as showing you and the GUI here, you can write them into a text file just in case there's a crash or your PC shuts down or something like that.
As mentioned earlier, finding such expired domains can prove to be a daunting task especially if you don’t have a tool to make that process a walk in the park for you. Instead of spending your time searching for tools that you are not even sure will help you find expired domain names with lots of traffic and backlinks, how about you try a game-changing tool integrated into Webfire 3.0 software called Expired Domain Finder and make your expired domain search a lot easier?
If the domain name is not with any auction house partner (I think that’s what you’re saying), then you can use a drop catch service anytime: https://www.domainsherpa.com/domain-name-backorder-services/ They do not make your order public information as NameJet and others do by sharing how many bids are placed on a domain name and thereby driving interest.
The third option is the one that's the most time consuming but also has its benefits. It's like having a successful restaurant and buying another restaurant and operating them simultaneously. They're not the exact same restaurant, but both are popular in their own right and make you money. The same goes for Option #3. You could update the content on the old domain and sell the same products that you're selling on your current site. If you can get both sites to rank alongside each other in the SERPs, you're increasing your conversion chances and sales potential.
You can easily find domains using the best metrics available from Ahrefs, Moz, Majestic, SEMRush, Similar Web, SEMrush, Domain Scope and Social Networks. We buy only the best, the latest, and, the most comprehensive industry wide metrics so you have the maximum amount of information to make a decision. No other tool gives you access to 90+ metrics.