Unfortunately, I think these questions come with answers that most people don’t want to hear. From what my sources tell me, Activision has marked Ninjini as a “Rare” Skylander. This does not seem to bode well for the casual collector or casual gamer.
Ninjini was first released to the public on February 5, 2013 at the NYC Toys R Us store. For one day they literally gave away their limited supply of Ninjini figures. These figures quickly ended up on eBay and Amazon with sellers asking exorbitant prices.
Since that time I have heard rumors of Ninjini figures being found in extremely limited supply at other Toys R Us locations. I have no proof of these releases and I haven’t seen any myself, but I wouldn’t be surprised if all we see is a slow, steady trickle of Ninjini figures infiltrating the market over the coming months.
Any other Skylanders figure I would imagine you’ll be able to find in stores or online for a reasonable price eventually, but you might just have to be willing to invest a little more if you want to add Ninjini to your collection.