It's ranking high today! What could be the problem? NO. JUST STOP. Unless you know the entire history of a domain, you may be setting yourself up for failure before you begin. SEOs (and business owners) use a variety of tactics to get a site ranking high in search results. For some of these methods, we'll just call them "questionable". These methods could include everything from buying links, overuse of directory submissions (non-industry related), duplicate listings, poor quality backlinks, and guest blog comments.
However, I'd argue that most people in the business really struggle as they don't understand what makes a good domain name and what's a bad domain name. While I do not work in this field full-time, I can say that I can make a living of it, but it's probably because I don't ask for absurd prices (e.g. domain name for $8000 is just unrealistic and won't happen) and therefore can sell domains easier. 
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.

Since 2013, more than 183 million domain names have been registered but none of these is used. A large chunk of these domain names is hoarded by domain flippers who will then resell these domain names to new buyers. Now if you are a newbie in this particular field, the best way to go about flipping domains is to start with a small budget until you gain relevant experience in the field.
Be careful! When searching for domains, it might be tempting to, for instance, buy (if it were available) and then try to sell it to McDonald's. The logic here would be that they own the .com and wouldn’t want anyone to own the .net and use their name, right? Also, it’s a big name so there’s gotta be a biiiiiiig payday comin’, RIGHT? Wrong, and wrong.
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Internet users, who try to find expired domains and re-register them, will soon discover that this plan cannot be manually accomplished. Professional domain traders are familiar with the registry deletion process and rely on sophisticated algorithms that indicate when a domain is about to become available. Deletion lists are the result of this research. You can find many datasets online with domains that have already become available or will soon be. You often have to pay to be able to see this information.
That’s it for deleted domains which you can just pick up by heading over to your favorite registrar and registering it right away as long as it says, free and green here. If it says registered it’s obviously taken. This is obviously a cheap way to get some great links because let’s say, you know, this site we saw is not bad. It doesn’t have page rank, but that could be just because there was no content on the site. If it has a solid link profile, you can be sure that the page rank will come back and you can pick it up for about $10.
Some buyers are a tough nut to crack and they may quote a ridiculously low offer. Explain to these buyers and convince them why the domain is worth more than the quote. If the potential buyer doesn’t agree, fret not, just move on to the next one until you find a willing buyer. Once you finalize the deal, then it’s time to find the best payment mode for the transaction.
In today's SEO (2015) the answer would be a big no! With changes to the google algorithm and the constant updates panda, penguin, what's next...., much of the "keyword url" power is now gone. While there was a day when it made sense to buy a good named .com and expect instant indexing, not so anymore unless the site is very strong coming in ,which in that case you'll drop a minimum $50k. If you are willing to drop that kind of money and the site has a high domain authority, it might make sense as long as it matches whatever product or service that you're trying to sell. Just my opinion...
In theory, you could technically acquire a domain for $10,000 and be able to sell it for $100,000. You could also acquire a domain for $10 and be able to sell it for $100,000, $10,000… or $100, you get the picture. Because of this, it’s hard to recommend a perfect starting budget because your strategy, experience, and the pace at which you learn will hugely affect your buying and selling decisions.