I got mine from glasgow angling for £2.50 plus postage but had ordered a few other things so it wasn't a big cost. Your other option is to get naphthalene mothballs from somewhere like ebay where you can get them for about £2 posted for approx 28 balls. This is basically formed balls of the crystal that you can use as they are, or crush and treat like crystals. Bear in mind that they basically evaporate in air so keep them air tight when not in use.
Depending on the amount of material you have then storage is up to you. If it is pretty small then you can get large air tight food boxes that are perfect. I use these to "quarantine" found feathers and animal fur dubbing (brushing the cat gives a nice fine grey/ginger dubbing mix and cuts to my arms

) etc for a while before they go near my other stuff.
I use a large leather effect shoe box type thing I got in B&M for about £3.
It's not airtight so not as effecient for the naphthalene but I find I get a good enough build up of gas to ensure a nice strong odour when I go in to get out my materials. I do store the materials in zip lock bags as well but don't seal them fully to ensure that they are exposed to the gas. You can sprinkle a few crystals into each bag and seal them to get 100% guarenteed exposure for all your materials but I find that exposure using the above technique is sufficent.