at the moment i can not recall the most expensive thing.
but i have 2 sentimental things:

i have this winter hat i am attached to.
the first one 1 lost in the buss near school.. i bought a new one, wich i lost on my way home in the buss in sweden :l i avoid busses when i have that hat on.

a Tamagochi, wich landed in the toilet :l it was beyond saving