I was thinking... maybe dense special materials should be priced as bonuses instead of flat price modifers? It would certainly make orichalcum/neutronium artifacts easier to handle, rather than having to calculate for the total cost of the whole item with flat price modifiers. If we do this, then these would be the price bonuses for orichalcum and neutronium:
Orichalcum/Neutronium/Dark Matter/Black Hole Matter Weaponry: Bonus^2 × 20,000 gp
1/262,144th Orichalcum: +180,000 gp => +3 bonus
1/32,768th Orichalcum: +720,000 gp => +6 bonus
1/4,096th Orichalcum: +1,620,000 gp => +9 bonus
1/512th Orichalcum: +2,880,000 gp => +12 bonus
1/64th Orichalcum: +6,480,000 gp => +18 bonus
1/8th Orichalcum: +11,520,000 gp => +24 bonus
Pure Orichalcum: +25,920,000 gp => +36 bonus
1/2,097,152th Neutronium: +46,080,000 gp => +48 bonus
1/262,144th Neutronium: +103,680,000 gp => +72 bonus
1/32,768th Neutronium: +184,320,000 gp => +96 bonus
1/4,096th Neutronium: +414,720,000 gp => +144 bonus
1/512th Neutronium: +737,280,000 gp => +192 bonus
1/64th Neutronium: +1,658,880,000 gp => +288 bonus
1/8th Neutronium: +2,949,120,000 gp => +384 bonus
Pure Neutronium: +6,635,520,000 gp => +576 bonus
Dark Matter: +11,796,480,000 gp => +768 bonus
Black Hole Matter: +26,542,080,000 gp => +1152 bonus
Orichalcum/Neutronium/Dark Matter/Black Hole Matter Shields: Bonus^2 × 10,000 gp
1/262,144th Orichalcum: +2,500 gp => +0.5 bonus?
1/32,768th Orichalcum: +10,000 gp => +1 bonus
1/4,096th Orichalcum: +40,000 gp => +2 bonus
1/512th Orichalcum: +90,000 gp => +3 bonus
1/64th Orichalcum: +250,000 gp => +5 bonus
1/8th Orichalcum: +490,000 gp => +7 bonus
Pure Orichalcum: +1,210,000 gp => +11 bonus
1/262,144th Neutronium: +5,290,000 gp => +23 bonus
1/32,768th Neutronium: +9,610,000 gp => +31 bonus
1/4,096th Neutronium: +22,090,000 gp => +47 bonus
1/512th Neutronium: +39,690,000 gp => +63 bonus
1/64th Neutronium: +90,250,000 gp => +95 bonus
1/8th Neutronium: +161,290,000 gp => +127 bonus
Pure Neutronium: +364,810,000 gp => +191 bonus
Dark Matter: +650,250,000 gp => +255 bonus
Black Hole Matter: +1,466,890,000 gp => +383 bonus
Orichalcum/Neutronium/Dark Matter/Black Hole Matter Heavy Armor: Bonus^2 × 10,000 gp
1/262,144th Orichalcum: +1,440,000 gp => +12 bonus
1/32,768th Orichalcum: +1,960,000 gp => +14 bonus
1/4,096th Orichalcum: +3,240,000 gp => +18 bonus
1/512th Orichalcum: +4,840,000 gp => +22 bonus
1/64th Orichalcum: +9,000,000 gp => +30 bonus
1/8th Orichalcum: +14,440,000 gp => +38 bonus
Pure Orichalcum: +29,160,000 gp => +54 bonus
1/262,144th Neutronium: +104,040,000 gp => +102 bonus
1/32,768th Neutronium: +179,560,000 gp => +134 bonus
1/4,096th Neutronium: +392,040,000 gp => +198 bonus
1/512th Neutronium: +686,440,000 gp => +262 bonus
1/64th Neutronium: +1,521,000,000 gp => +390 bonus
1/8th Neutronium: +2,683,240,000 gp => +518 bonus
Pure Neutronium: +5,990,760,000 gp => +774 bonus
Dark Matter: +10,609,000,000 gp => +1030 bonus
Black Hole Matter: +23,963,040,000 gp => +1548 bonus
I didn't do conversions for Medium and Light armor because they didn't seem to follow the Bonus^2 × 10,000 gp price formula.
I'd also like to ask about the method of pricing for shields and heavy armor. They seem quite random compared to the weapons which simply use a staggered doubling. How was their price bonus determined?