a clean and long headstock break might be around £125 but that one is going to be more because there is no easy glueing surface to use help stick it back together.
on a clean break you can do a simple clean up, reglue and touch up - this wouldnt be that simple.
i didnt know what price these go for but if its around the £500-600 mark then £400 is definately too much
personally if it was my guitar i would rather replace the whole neck than reglue that headstock - Just for long term survival and stability
+1
that break is beyond tough to repair - more so than a typical Gibson headstock break.
The break is a short one rather than a long splintery one (which would at least give you some surfaces to glue back togetheer.
On this guitar I wouldn't try to get that headstock to go back on (and I suspect that the current owner knows how impossible it would be as well)
It really requires a new neck to be made and installed, which requires some pretty careful work digging out the old one, and maybe having the headstock face trimmed down to 0.25" and added to the front of the new headstock.
The while guitar would need refinishing too to look right , so all in all it's a tricky and expensive job.
You are buying a case and some hardware bits to be fair
Spending more than £200 would be a false economy rather than just buying an intact guitar
