If you buy a dropped domain from Snap or Namejet, the backlinks seem to be worthless for SEO.  They are valuable for traffic if it's targeted to your site.  Go ahead and 301 redirect into your site because it's the traffic from the back links that is worth something.  I use the Google URL builder to redirect these names so you can see the domain the traffic is coming from.

If you are looking to sell a domain name that is no longer of use to you, a possibility would be to lease it through a third-party company such as Godaddy, which lists tens of thousands of names. If the name is a quality one, there are also premium agents such as MediaOptions, which deals with more selective domain names. An alternative option would be to lease it out on platforms such as Nameforest.com. Doing so will save you the time of having to find potential buyers, and will guarantee a higher success rate than attempting to look for a purchaser on your own.
Review Web Archive’s versions of the website: Examine the website’s history and how it looked like using the Web Archive. What was it about? What did it offer? This is useful for a variety of different reasons. It could inspire you as to who a good potential buyer might be (by analyzing the website’s content), and it could also signal some red flags in case the domain was being used for anything shady.
Many people think of domain buying and selling to be one of the easiest methods of making quick money. Perhaps, you may have heard of someone buying a domain name for under $3000 and then selling it for $25,000. A quick $22,000 profit! Such stories can be very motivating! And that sort of money does exchange hands (Go through 10 of the biggest domain name sales of all time!). But these deals don’t come as easy as they seem! Ask anyone who flips domains for a living and he/she’ll tell you the amount of hard work and skill that goes into it.
Also with the domains, a name which can be cheap for one can be worth gold for the other. Permute the letters in your domain name and try contacting and eventually selling out to organizations that run under those names or contain the letters within. Companies would be keenly interested in buying out the domain names that matches the product's name. Hint : Look for companies on LinkedIn
There is a misconception that good ‘.COM’ domain names are hard to find and so they are more expensive to buy. But once again, this statement holds no water. You can easily check out the ‘.COM’ domain names that are on sale at highly affordable prices. However, the only downside to flipping ‘.COM’ domain names is that you will have to discover them at different places like Flippa.com or private seller portfolios.
One big tip is to find a domain that someone can make money with. If you only owned that 1 domain, could you earn a living? This helps you focus on the top 1% of domains and ignore the junk that you will struggle to resell. You must get this right because domaining can bankrupt you fast if you buy the wrong domains. Godaddy is also great for grabbing expiring domains for much less.
Know your rights under the Anti-cyber squatting Consumer Protection Act (ACPA). This is the main federal law that deals with domain name trademark disputes. These distinctions are still a legal gray area, and being able to make these claims is no guarantee you will win a case. You should consult with a copyright lawyer to help determine the validity of your defense. If you are accused of cybersquatting, you may be able to keep your domain if you can make any of the following defenses in court:
Contains, Starts, Ends You can use the search bar to search for domains that contain particular keywords you are seeking, e.g. a search for "car" will yield results for all expired domain names that contain the term "car". You can also use the search tool to find domains that begin, or end with the search term too, with the drop down box next to the search form.
Dictionary Word/Pronounceable/Memorable/Brandable: A dictionary word domain name is very valuable. Of course, the more popular and widely used the word is, the better. For example, “marketing.com”, “cars.com” and “hotels.com” are 7-8 figure domain names. Even if a domain name isn’t a dictionary word, being pronounceable and/or memorable and/or brandable are all big pluses that add to its value.