I don't necessarily agree with some that dropped domains don't have value for SEO purposes but either way one thing you can do is to check out our tool for finding auction domain names (the tool has a database of domains available buy from GoDaddy and SEDO and also give additional SEO criteria to look up for the domains like backlinks, Compete data, CPC, Google stats, Alexa stats, etc. and there is also an option to schedule auction domain alerts so that you can be notified via email if a domain name meeting criteria you specify gets put up for sale) or you could use our tool fo domains dropping soon that shows all domains dropping in the next 5 days that way you can be ready to snap them up right away.
Listing on domain marketplaces: This is the most common route. You should, however, acquaint yourself with each marketplace’s policies and fees before deciding to work with them. For example, Sedo’s commission starts at 10% and BrandBucket prohibits listing the domain anywhere else if you’re selling with them. Here’s a list of the most popular marketplaces (in no particular order):
A rule of thumb that I follow is when I purchase a domain name I have to believe that I can flip it for a 100% profit.  So if I spend $500 on a domain I need to feel like I can sell it for no less than $1,000.  This way, even if I’m wrong in my estimation I still have some room to still turn a profit.  And if worse case comes to worse case I’ve sold domains before for a $0 profit (it happens even to the best of us).
Just because someone spent five or six figure amount on a domain name doesn’t automatically imply that he/she’ll spend the same or at least a few thousand dollars on a similar name too. Basing your domain flipping strategy entirely on what others have just bought may not be as useful as you may think. Every domain name has a story behind it and its purchase/sale is usually as unique as that story.

Your system is broken, You took my lising money on an open domain http://www.australianfintech.com.au and then stuffed me around something cronic and no response from your supoport team either. I have spoken to Tony who is one of the main people there at a function and I will move heaven and earth to find his number and give him a piece of my mind!! I have 60+ domains to sell but it seems you do not want the business! BAD MOVE not accomodating clients!

The market-driven principles of the domain trade mean that a domain is only worth as much as the buyer is willing to pay. It is for this reason that criteria such as market potential and usability play such central roles in determining prices. Values can change at the drop of a hat. The price of a domain that was once of little interest to anyone in years past can skyrocket once, for example, a newly founded company takes interest in that same name.
Unfortunately, most domain names take at least a couple of months to sell, especially without an attached website. Thus, there is no need to become discouraged if your domain name does not sell immediately. Most people make the mistake of quitting their domain speculation endeavor after waiting for several months to sell without success. In reality, domain name squatting can be just as profitable, and it is a valid form of long term investing.
Using the keyword search feature you’d also be able to familiarize yourself with how much domains typically cost on average in a certain industry or niche. Even better, they have an addictive little app called “The Domain Game” available for iOS and Android. They basically give you a domain and you try to guess whether it sold for three, four, five or six figures. You get points for each correct answer and lose points for incorrect ones. You do this for a while and you start to see patterns. Your brain starts connecting the dots and you get better it. Now you’re ready to go out there and scout some domains!