This is... disturbing.

[Spatzimaus]

Restricting to Mage Class only detracts 30% of the cost..

450 * .7 gp + 36 *.7 XP

315 gp + 25 XP

To paraphrase one of the developers and a lot of people on these boards: If you're designing an item for a specific person (yourself, your party members, etc.) you shouldn't get to take the 30% off, since it's not actually a penalty for you. I mean, I'd love to make all my items only work for a Female Half-Elven Psychic Warrior with 14 STR, 16 DEX, 5 ranks of Tumble, and red hair. It'd be better than Lo-Jack; no thieves would ever bother with me, since the items would be useless. Sure, I wouldn't be able to sell the items, but with the way items upgrade in 3E, why bother? Just keep stacking more abilities on.

Restricting your item to mages isn't a drawback, it's a bonus. The discount was intended for restrictions that make sense, like needing Scry to use a crystal ball or needing to be good to make Celestial Armor.

 

[pawsplay]

Right, restrictions should generally only be worth a discount if, a) they are a logical requirement (such as Perform for an instrument or paladinhood for a holy avenger), and b) the item would otherwise be interesting to some other member of your party. If only one or the other is true, no discount, and if your item only serves "the line of Radomir Bluehair", you should probably add about 2000 gp to the final retail price, like a fairly stupid intelligent item.

 

[Mark Chance]

Prerequisites: CL 15, Craft Wondrous, Launch Bolt Spell, Silent Spell, Still Spell, Eschew Materials
Creation Price: 300 gp & 24 XP

As has been pointed out, and thus I'm joining the chorus, your DM doesn't know what he's doing. CL for an item is not a prerequisite. For a command word activated item, there is no need for the various metamagic feats listed.

As for what I'd do? I'd tell my DM: You don't know what you're talking about. That's not how item creation works.

 

[Hypersmurf]

If you're looking for a 1/round creation of a crossbow bolt, still, there's a Metacreativity 0-level Psionic power called "Bolt" that does exactly that.

-Hyp.