the pump itself is pretty basic mechanically - the drive system on the pump is what is expensive.
If you tear apart one - you will find a bread and butter bosch VE pump design. just like when you tear apart a 1KZ-TE pump.
some people go to the extent of using a mechanical injection pump on both above engines and then wonder why their truck has all the power of a smoky low compression honda 50 engine pulling a fat doodh wala and 4 bottles of milk.
btw - 400K yen is not too bad for this diesel injection pump be honest, try sourcing a new front diff or something similar for a land cruiser