This will be quite useful. Thanks for making it.

I figure I should help some if I can, so I'll try to suggest some prices for items on your to-do list.

Wand of Fireballs/Lightning Bolts: ~26000
Reasoning: This is in between the Staff of Fire, and the Wand of Polymorph, which are less powerful and more powerful, respectively. I would put these at about the same power level as the Staff of Frost, which is why I suggest the same price.

Wand of Magic Missiles: 8000
Reasoning: The Wand of Web costs 8000, and it's a 2nd level spell. A wand of a first level spell (which can be cast at higher levels for more charges) seems to be about equivalent in value to me. If anything, 8000 might be a little high of a price.

Manual of Golems: >31000
Reasoning: Elementals are CR 5, so having the ability to create Golems of CR 5 or higher needs to be the same price or higher than Rings of Elemental Command.

I have listed the suggested prices for the items I did not see on your list below. This assumes that the Robe of Useful Items is too random for pricing, which is why I did not price it.

Dragon Slayer: 7000
Reasoning: It's similar in function to a Giant Slayer, and you've got that priced at 7000. It might warrent being bumped up to 8000, however, because it is especially good against some of the most dangerous monsters in the game.

Mace of Terror: 8000-10000
Reasoning: It has nearly the same effect as the Wand of fear, but in a radius. I lacks the wand's other option, so a lesser price may make sense.

Once again, thank you. This will be very helpful.