Sorry to be slow, I'm having trouble getting motivated.
Ison has 18 spellcraft, so can't tap DC25.
Assuming there is a way and to make the Jingasa and you want to
take the chance of failure -
it seems Ison will spend 182 days crafting for the party members.
I think I will make the wand of haste extended, so another 10 days
and 4875gp from party treasure, or Ison will cover it.
Ison take from treasure:
blessed book 12500gp
scroll dimension door 750gp
belt mighty con +2 2000gp
Ison will craft for himself:
handy haversack 1000gp 2days
wand of magick missle with dazing metamagick 10500gp 21days
(would make these mythic if I could - is that possible?)
ring of prot +1 to +3 8000gp 16days
amulet of nat armor +1 to +3 8000gp 16days
cloak of resist +2 to +4 6000gp 12days
total cost 40750gp, 67days
This will leave Ison with 4109gp + 3434gp(already had) = 7543gp
and 106days which he will use to hopefully learn some more spells, write some scrolls, and do research on the possibility of including sonic in the admixture versatile evocation.