Just to make things difficult, Carioca (a well known drawing pens maker) has released a set of 14 Smurf erasers, each with a different subject pictured on a big (about 10 cm by 5 cm) eraser.
The funny thing is that they are sold inside a wrapper, so you don't know which one you get.
I bought 4 of them and found already a double: Papa Smurf!
I've sent an e-mail to the customers service in order to know if there a chance to get a set from them without having to go and buying 'doubles'.