Hello Mark.

A difficult one to value due to the present market and the fact it has been de-Nazified.

I would suggest that you look at some dealer sites for parts they sell. This would give you two options.
I. Buy another Eickhorn XGuard of the same type (might be difficult) and make it whole again.
2. Add the sum of the parts together IE blade (tapering tang),Scabbard,grip,pommel and ferrule.Subtract around 20%. Bobs youre uncle you have a figure to play with.

As I am UK based a Dollar value has no relation to the current Sterling market here and the Euro market abroad.