It's crap, I did say G-Sync is expensive. But it's justified for lack of better phrasing because of the extra hardware in the monitors. Adaptive Sync is an updated DisplayPort, a port type that is already common on monitors. No one has had to pay for this, DisplayPort is royalty free, so a £180 price rise is unjustified.
If that little box is not what makes G-Sync so expensive then tell me what does make it so expensive...
Isn't it actually a £100 price drop over the equivalent G-Sync monitor?
As to what it is that makes the G-Sync monitors so expensive.. You can only look to Nvidia. There's absolutely no way the g-sync module costs £100 to manufacture.