I'm not against making money in any way, but $400 doesn't really seem worth the effort and coffee expense invested (I like the good stuff). This is a very basic example used to put the costs in perspective. Most SEO providers charge more than $50 per hour, and you get what you pay for. The above example of a final labor estimate is probably much higher, or if the domain is already ranking high and the owner wants to sell, so is the initial purchase price. Since this is often repeated many times over for multiple domains, it could get time consuming, and expensive.
It’s also not so easy to manually re-register. This is due to backorder providers which are paid to keep an eye on expiring domains over a certain period of time and then register them for the customer as soon as they become available. Promising expired domains are therefore usually sold before they have a chance to be put back on the registry menu for the public to look through.
Sellers should also learn to identify premium domain names. Dictionary names are premium domain names. Domain names with dictionary-singular names are the hottest on the Web, and buyers are willing to pay a lot to purchase them. Names, such as search.com or askme.com, will get buyers more easily than long domain names. It is also important to note that unhyphenated domain names have more value. Even product-related domain names also can enable sellers to earn substantial profit. Once a seller has a certain degree of knowledge about the domain, he can start searching for buyers.
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!

There’s an important distinction to make here between domain flipping and website flipping. The latter mainly refers to buying and selling full websites. By full websites, I mean websites that actually have content and more often than not have traffic and revenue. When buying and selling websites, the domain name matters less as the main value there is the content, traffic, revenue, history/reputation, sustainability and growth opportunities. The same can’t be said for domain names where you’re just selling “the name” and hence it’s all that really matters.