Are lower-end phones just as moddable as flagships? After a long time in the waiting, I finally have an excuse to upgrade from an iPhone (5s) to an Android. As a tech enthusiast and general superuser, the freedom to do what I want as far as customisability and general tinkering with the software is almost entirely the reason I've gone off iPhones and am looking for an Android. I'm bored of playing in the garden and it's time to climb the wall.

However, I'm also on a low income, which means I'm still very much limited by budget (less than £200, let's say, although the lower the better), and as someone who knows very little about the Android mobile market, I'm wondering how realistic it will be for me to satisfy both desires in a single phone. 

I'm not asking for product recommendations per se, just wondering in general terms, based on the state of the market, what the situation is. Are most phones of this range just as malleable software-wise as flagships, or are they not? If they are, which ones in particular should I avoid?
You should avoid some Flagship device's... 
Samsung's use a security feature called Knox, that'll make thing's harder.   Some newer androids 5.1+ will have extra security to stop system modifications... 

In my opinion you are better off looking for a device that's running below Android 5.1 and uses an MTK Cpu, this is because most of the new security features to stop modifications hadn't been implemented yet.  

Theirs practically no difference in the actual Android system when comparing manufacturers, if its using Android 4.4 it's the same on a more expensive device running 4.4, however their is differences when it comes to each device, some ( Samsung's use Knox ) to lock things down even more... 

You should definitely be open to device suggestions because some devices are simply better for modifications.



Main Price Difference Causes    


OGS - (One Glass Solutions) Screen Thickness   
IPS - Viewing Angle Of Screen   
CPU Capabilities - Speed &amp; Support for games
RAM - Obvious price impact   
OTG - On The Go Support - Usb Device's
Dual Camera - (Tri Camera) - Face, Back, (Focus Assist)
Back &amp; Front Camera MP - Size of photos    
Finger Print Support - Security   
GPS 
Gyroscope 
Mobile network radio band support
Full HD - 4K Screen Definition ( Retina Display )
Full screen width ( Edge to Edge ) 
Other non essential enhancements....


If you don't mind about support or inclusion of any thing above and some other's, the price doesn't really matter.