user14276: I am looking for a cheap (not necessarily free) editing software.
At the moment I have to work with Serif MoviePlus X6 but I find this too basic.
I have a lot of knowledge of video editing but am usually restricted by the limitations of the software I can afford. I need something as advanced as After Effects - and similar to Blender's layout which is NOT designed for ease of use but rather to offer as much flexibility as possible - for general video editing; but for a lower cost than Adobe products.
Any suggestions?

ANSWER
Of the amazing answers I received I found the best suggestions were:

BlackMagic Davinci Resolve 12
Lightworks


user6273: Since you said you use Blender for animation, why not just use that? Feature-wise, it's video editor can stand on it's own. It's a nightmare in usability (in my opinion, I believe that's also the general consensus), but if you're used to the program anyway ...
Free software
There are a couple of free programs available (a list, another list), most of which suffer from the same problem as Blender, that is not having a coherent design which leads to inconsistensies in it's functionality. It might take longer for you to get a grip of the software, and certain functionality might be missing. So if you're willing to invest some money, you can probably do better (even though it mostly comes down to preference).
The low-cost software trap
Be careful with cheap software (for example, Magix software), as it's most likely consumer oriented and not fit for (semi-)professional editing. The problem with those programs is that they are not built for editors who are willing to put some time into learning the software and fine-tuning effects and settings, but rather for people who just want to throw their vacation video together, add a title, some background music and be done with it. That means advanced functionality such as keyframe animation will probably not be available and in terms of visual effects you will most likely be tied down to a couple of presets. 
It comes down to what you want to do, what functionality you need and personal preference.
Some affordable candidates

Sony Vegas (at least Pro)
Final Cut X
Lightworks
Corel VideoStudio Ultimate
Premiere Elements

Please note that this list is influenced by personal preference (I use that word a lot for a reason). Again, it comes down to what you need. Also, all of those low- to medium-cost options are to some degree limited, i.e. might lack certain functionality. None of them will compare to professional software such as Premiere Pro and After Effects. Final Cut X and Sony Vegas Pro Suite probably come closest to it, whereas Corel VideoStudio and Lightworks would be somewhere in between professional and consumer software. Premiere Elements is pretty easy to learn, but lacks most functionality that you will need for professional/advanced editing.

user6921: Lightworks (as mentioned previous) but also newcomer to the game is BlackMagic Davinci Resolve 12 which can be both Free and Paid (if you want all the PRO Pro Features)

user14359: Hitfilm has a free express version and a paid version. 
It's a video editor and a compositor. 

14276: <p><strong>I am looking for a cheap (not necessarily free) editing software.</strong><br />
At the moment I have to work with Serif MoviePlus X6 but I find this too basic.<br />
I have a lot of knowledge of video editing but am usually restricted by the limitations of the software I can afford. I need something as advanced as After Effects - and similar to Blender's layout which is <strong>NOT</strong> designed for ease of use but rather to offer as much flexibility as possible - for general video editing; but for a lower cost than Adobe products.</p>
<p>Any suggestions?</p>
<hr />
<h2>ANSWER</h2>
<p>Of the amazing answers I received I found the best suggestions were:</p>
<ol>
<li>BlackMagic Davinci Resolve 12</li>
<li>Lightworks</li>
</ol>
 6273: <p>Since you said you use Blender for animation, why not just use that? Feature-wise, it's video editor can stand on it's own. It's a nightmare in usability (in my opinion, I believe that's also the general consensus), but if you're used to the program anyway ...</p>

<h2>Free software</h2>

<p>There are a couple of free programs available (<a href="https://softwarerecs.stackexchange.com/questions/11433/freeware-video-editing-software">a list</a>, <a href="http://tv.isg.si/site/?q=node/873" rel="nofollow noreferrer">another list</a>), most of which suffer from the same problem as Blender, that is not having a coherent design which leads to inconsistensies in it's functionality. It might take longer for you to get a grip of the software, and certain functionality might be missing. So if you're willing to invest some money, you can probably do better (even though it mostly comes down to preference).</p>

<h2>The low-cost software trap</h2>

<p>Be careful with cheap software (for example, <a href="http://www.magix.com/us/movie-edit-pro/" rel="nofollow noreferrer">Magix software</a>), as it's most likely consumer oriented and not fit for (semi-)professional editing. The problem with those programs is that they are not built for editors who are willing to put some time into learning the software and fine-tuning effects and settings, but rather for people who just want to throw their vacation video together, add a title, some background music and be done with it. That means advanced functionality such as keyframe animation will probably not be available and in terms of visual effects you will most likely be tied down to a couple of presets. </p>

<p>It comes down to what you want to do, what functionality you need and personal preference.</p>

<h2>Some affordable candidates</h2>

<ul>
<li><a href="http://www.sonycreativesoftware.com/vegassoftware" rel="nofollow noreferrer">Sony Vegas (at least Pro)</a></li>
<li><a href="http://www.apple.com/final-cut-pro/" rel="nofollow noreferrer">Final Cut X</a></li>
<li><a href="http://www.lwks.com/" rel="nofollow noreferrer">Lightworks</a></li>
<li><a href="http://www.videostudiopro.com/en/products/videostudio/ultimate/" rel="nofollow noreferrer">Corel VideoStudio Ultimate</a></li>
<li><a href="http://www.adobe.com/de/products/premiere-elements.html" rel="nofollow noreferrer">Premiere Elements</a></li>
</ul>

<p><strong>Please note that this list is influenced by personal preference</strong> (I use that word a lot for a reason). Again, it comes down to what you need. Also, all of those low- to medium-cost options are to some degree limited, i.e. might lack certain functionality. None of them will compare to professional software such as Premiere Pro and After Effects. Final Cut X and Sony Vegas Pro Suite probably come closest to it, whereas Corel VideoStudio and Lightworks would be somewhere in between professional and consumer software. Premiere Elements is pretty easy to learn, but lacks most functionality that you will need for professional/advanced editing.</p>
 6921: <p>Lightworks (as mentioned previous) but also newcomer to the game is BlackMagic Davinci Resolve 12 which can be both Free and Paid (if you want all the PRO Pro Features)</p>
 14359: <p>Hitfilm has a free <a href="https://hitfilm.com/express" rel="nofollow">express version</a> and a <a href="http://hitfilm.com/pro" rel="nofollow">paid version</a>. 
It's a video editor and a compositor. </p>
