Lately I've noticed a lot of questions in Q&A centering on purchasing expired domains. A lot of our members have expressed interest in buying old domains for a variety of prices (some are cheap, some are going for upwards of $50k) and want some advice on what to do with the domains once they've been purchased. I'm no domainer, nor am I an expert in such a business tactic, but I generally recommend one of three different options for an expired domain (and would love to hear more if you've got any).
Why does this matter? What's the big deal? Well, unfortunately, the vast majority of domains registered are eventually abandoned. For some reason or another, people just fail to re-register or renew their domain name and that domain name drops or becomes available to the public. Of course, the obvious reason is that these people simply did not make money off the website that they put up with that domain. Other bloggers and website owners simply don't have the time, so they just gave up on their online projects. Whatever the case may be, by simply registering these expired domains, you can resurrect the value they bring to the table. With the four situations that I outlined above, you can benefit from those situations by simply registering a drop domain.

Domain name market is heavily oversatured these days. There are more than 80 milion domains registered in total. Finding a right domain name is sometimes nearly impossible task, especially if you are not willing to pay extra cash to buy a domain that is already grabed and now for sale. If you have already tried to type in domain names for availability you probably had zero success, especially if you have searched for more generic words and keyphrases. The author of this program remembers he searched virtually for weeks to find some more or less usable names that he could use, and that was years ago. Since then, finding a good domain have gotten harder. Much harder.
The easiest way to see that is to go to HREFs and look at the anchor text. It reveals right away whether or not the site has been spammed. You also want to see if it’s been SEO’d too much. Right? In this case, it’s not because it has a brand name here and some natural keywords, but if the number one anchor text was like, cell phone management system and then the next one was like cheap cell phone management system, you’d know that the anchor text was manipulated and probably overly SEO’d. So, what you want as a site that has a natural link profile.
At the end of the day, this article is geared to startups, business entrepreneurs, webmasters and marketing professionals who need to understand the process, and I guestimate that the process listed in the article above accounts for 99%+ of all expired domain names. All of your points are valid and appreciated, but if someone is interested in buying a good, brandable domain name for their business, they should follow the instructions above to have the best chance of grabbing it.
SEO is not as easy as it used to be. The market is very saturated now, content is now incredibly easy to generate and publish. Everyone and his dog (or gran!) can make a wordpress website. The main ranking factor for Google is still backlinks and will be for the foreseeable future. Your content might be better than your competitors but if they have more links they'll simply always outrank you and receive more traffic. Fair or not, its a fact. This method can see you get the strong backlink profile you need to rank #1. Please note a PBN is considered black hat so please diversify your backlink profile and do your research first.
Most popular auctions with expiring domains are at godaddy, namejet, snapnames. Search for expired domains name its very easy if you have domains list. With a bit luck, you can drop good one with PR5 cheaper like $200, just need to know which domain have not fake pr. List of domains are not free, but updated dailly with aprox. 50.000 new expiring domain names.

Domain name search results appear as you type. We can do domain lookups very quickly, and usually show domain search results in less than 100 milliseconds. We generate domain names and check .com and many other domain extensions instantly. We use artificial intelligence techniques to find domains for sale that you can buy today and expired domains to backorder. Just start typing!
Most popular auctions with expiring domains are at godaddy, namejet, snapnames. Search for expired domains name its very easy if you have domains list. With a bit luck, you can drop good one with PR5 cheaper like $200, just need to know which domain have not fake pr. List of domains are not free, but updated dailly with aprox. 50.000 new expiring domain names.
The great thing about this is that it’s kind of like a metasearch engine for all the places that you can find expired domains around the web. First, let’s look at deleted domains. Okay? To do that, you go click on the deleted domains button here and then click on any top level domain that you want to get. I prefer .com because it’s obviously the most common top level domain.

The better quality links (From Google, Wikipedia) that a website has the higher will be its domain authority. New websites start with a ranking of one, and as the number of links increase the domain authority rises. For example, a sports website that has links to sports newspapers and sports reporting sites will have a higher domain authority than a sports website that only has links to other sports and sports blogging sites.

By strategically buying expired domain names which have certain quality features, you can create a link "pump" to your target sites. From an SEO perspective, this can turbo charge your rankings on Google and other search engines. Also, you can make money directly by promoting products on high ranking search results. Additionally, you can make money by selling links on your network to people looking to get an SEO boost.
Here's an old post on search engine roundtable that claims google's policy is to discount previous backlink juice when a domain changes ownership.  I'm not convinced whether this is actually true or something Google says to discourage excessive domain buying / 301 redirecting for SEO benefit.  The comments above seem to give varying opinions on this matter. Would be great to get to the bottom of that one!
Since high quality expired domains are in low supply, the huge numbers of marketers competing for those drop domains tend to drive prices up. Also, if you use an exchange, you’re basically lucky to get whatever you can afford. In other words, niche specificity isn't guaranteed. This is going to be a problem because as Google continues to evolve, it is cracking down on domain niche relevance. In other words, its software is fast evolving to the point that it can tell what the niche of a particular domain is. If your private blog network is a patchwork of expired domains that involve many different and dissimilar niches, then you might be in trouble. You are at great risk of being penalized by Google.

To get the most from GoDaddy Auctions, you should first decide on the way you want to evaluate the domains. Domainers tend to look at the words in the domain name, while SEOs care about the backlink equity. If you are a domainer, you should look at Estibot, Domain Index or Valuate scores. If you are an SEO, you should look at the Ahrefs, Moz and Majestic metrics to gauge the value of the backlinks. Once you have figured this out, you should look at these numbers for every domain you find on GoDaddy Auctions. Do not be afraid of bidding on the Closeout auctions, as you can get good domains for cheap.