Microsim adapters SHOULD be FREE!
I got mine from a retail store here in sunny BCN, completely free. The guy from the shop took from behind the desk a bag with a few hundreds of them little black and inexpensive plastic things. And he gave it to me just because I asked for it.
(I didn't dare to ask for a spare one :o ).
So many of the posts on this thread are plainly from sellers to me. Maybe I'm mistaken but they all use similar construction and "hey guys" estilo.
Sorry for unearthing da brick. Just MHO.