looking for the cheapest way to store a fireball

[StDrake]

I'm up to no good and I could use a fireball out of the blue. Problem is - I'll probably not be having my partys spellcaster nearby when on the job and it's quite likely he won't have to level to cast one anyway..not to mention I'm not sure if any of them actually CAN do that.
I do know however that at least one of them will be taking Craft Wonderous Item and there's a good chance I'll be able to borrow an npcs wand, use it and put it back before anyone notices I've been doing something I shouldn't.

Now our resources will be limited, so I'm looking for the cheapest way to get a spell storing item. So far best I found was a ring costing 9k to make (+scroll cost for Imbue with spell ability)..quite a bit and it's a ring, but maybe we can craft something with the same functionality.
Any cheaper options? It's fine enough even if the item in question would be one use (funnier even if I can do that with bird feed or a similar dastardly thing ot just leave behind for someone else to activate by accident)

[Nipin]

necklace of fireballs

[Nipin]

another spell option to consider: explosive runes

[Imbicatus]

An old trick is to put fire trap on a small hand-held box with a loose, easy to open hinge, and then throw the box at an enemy. When the box hits, it opens and then boom.

This may meet with GM disapproval though.

[StDrake]

The thing here is about stealth and minimising the chance at myself getting the blame for the explosion so I'd prefer something capable of storing an actual fireball (for an area effect) and having a custom trigger (so i don't have to be around for it to work..at least not anymore)

[cnetarian]

While I could second the note which says "I prepared explosive runes today" a level 3 druid casting fire trap is cheaper, albeit the spell does only 1d4+3 damage versus the 6d6 of explosive runes. You could also use the trap rules to create a trap, but a trap would likely be more expensive than fire trap/explosive runes/symbol of death spells (well not symbol of death).

[Abraham spalding]

Potion of fireball?

Not your fault if they drink it.

[Wheldrake]

Delayed blast fireball is a thing, and will give you a few rounds to put it in the right place and disguise your efforts.

[Umbranus]

You could ask the GM if he allows a fireball version of a javelin of lightning. But it would need craft arms and armor.