You could try to sum up price for all its component and work from there. I have never seen this item traded.
A quick and rough estimates for each component in parenthesis:
Agito 1977 (1.5~3), 1980 (1.5~3), 1983 (1.5~3), 1991 (0.5~1), 2001 (0.5~1)
Musashi (0.5~1), Yamato (0.5~1), Asuka (1~2), Sange (1~2), Shichishito (1~2)
Kusanagi (0.5~2), Yata Mirror (0.5~2), Yasakani Magatama (0.5~1), Red Odoshi Domaru (1~2), Black Odoshi Domaru (1~2)
Kamui (1.5~3), Kamui (1.5~3)
These numbers are very rough and could be inaccurate, you might find that someone has a bunch of a particular item and don't think much of it and would sell cheap, or you might find that no one in the circle you're acquainted with has one. Personally I find the first 3 Agito and Kamui to be the hardest ones to get, the rest are Ep1/Ep4 drops that occasionally drops in people's runs, or are just easy enough to hunt. A lot of the items also are possible rewards in BPD.