I'm by no means an expert in pricing gear, but if I had to guess: Their full front end kits (Rail/barrel/delta assembly) go for around $130 + shipping / duty (lets say $180).
Lets say the rail is worth $120 of that equation. Less $20 for it being second hand. $100 would be fair.
Best of luck.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.