The Noctuary (D&D 3.5e, Level 20+ Adventure)

[AvatarVecna]

I'm looking to make metamagic rods that aren't in the books, but the DMG prices are inconsistent. The ones in Complete Arcane seem to (almost) follow a formula though:

Spoiler: math stuff

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300 * X * X * (1+(Y*Y))

X=maximum spell level that can be affected
Y=the level adjustment of the metamagic feat in question

Following this formula would indicate the following costs...

Level	3	6	9
0	2700	10800	24300
1	5400	21600	48600
2	13500	54000	121500
3	27000	108000	243000
4	45900	183600	413100
5	70200	280800	631800
6	99900	399600	899100

In Complete Arcane, the metamagic the rod of Sculpt Spell (+1) agrees with this formula 100%. The metamagic rod of Chain Spell (+3) is priced at 27200/108000/243000, which is so very close to being correct that the difference could be attributed to a mistype. Similarly, the metamagic rods of Cooperative Spell and Energy Substitution (both +0s) match the chart except their middle level is 10500 gp instead of 10800 gp, which could also be simply a mistype (albeit one happened consistently, so maybe the prices were copy-pasted?).

Is it acceptable to use this formula/table for pricing out metamagic rods that don't otherwise appear in the books?

Separate question, since I can't really find a straight answer one way or the other in the RAW: can one apply metamagic rods to spell completion/spell trigger items? If the answer is definitely "no" for wizards on the grounds that you think metamagic can't be applied to spells from items, can it be a "yes" for artificer since I have class features specifically allowing me to apply metamagic feats to spells from items?

Finally, requesting Easy Metamagic feat (dragon 325 pg 62).