> They charge by the kilo and the cost to dump a piano is over $75.

I've disposed of many-a-piano, including grands.  It's just a matter
of chopping them up into enough small pieces that you can put it out
at the curb little bits at a time over several weeks.  Eventually it
all goes away.  The university has a recycle center; I just break up
the plate into a few chunks and drop it off when I get the chance.
In fact, here you can see my YouTube video of chopping one up to take
out to the curb:  http://www.youtube.com/watch?v=KkROzK9yuAs 

Rob Goodale