Although I plan to eventually get myself some of the mini decks from Carte Karuta, I do have a few others that I bought locally. Two I found while browsing at Target -- are you in the US? If so, take a look down those aisles, often near the front of the store or near the kids section, where there are lots of little bins with cheap little stuff. Cards, toys, mini-games, etc. I found mini Bicycle decks there twice. If you find yourself in other "big box" stores, I'd check the same aisles in those, too, especially near Christmas time because they consider them good stocking-stuffers.
I also ordered a bunch of playing cards from Ellusionist, and got myself the Mini Ghost Bicycle deck. I've included a picture of that one below, since I already have it here on the computer. (I had a marathon picture session for a playing card thread here a while back!) Note that this one is colored differently.