Ugh, *some* computer shops tend to do that so they can milk out some money from you. The best recommendation would be a broad electronics store, where they sell not just computers.
Spray mounting.... grr. I hate doing that. I just print out my designs on sticker paper and just stick them on the item used for promotional purposes. I did that once on my first promo project, which was about Animal Cruelty. My second one, however was done on Anti-Justin Bieber. It came out successfully, and my total money spent was $50. lol
I was also thinking of a magic hat with a wand, but that sounds too common. A tarot card gives the pupil an idea that it's more of a Psychic's Shop rather than a magic shop.