Thanks for starting the ball rolling. You're a .
There are bound to be plenty of builders merchants around the island - especially near Corfu Town. The color=#800080 Babel Fish translator gives the translation for cement mixer as áíáìßêôçò ôóéìÝíôïõ ("anamiktis tsimentou") - but there may be a more commonly used slang term.
Also, if you ask your neighbours or someone at the local Mayor's office, or even at the local shop or Kafeneion, they may know of a builder who you could hire a mixer from for a week or so, rather than buying one.
Another option might be if one of the DIYers out there already has their own mixer that they've more or less finished with. If so, you might be able to offer them a fair price for it.