look at the big chains near you (marco polo - expert, unieuro, euronics, trony... there are many of them), you should get the best prices there.
you can also look on amazon or other online stores.

che coglioni, zave... veramente

ma porco dio zave veramente

ps: anyone know where to buy good movable air conditioning units in Italy?

These are the only real "movable" things you can get.

http://www.dyson.com/fans-and-heaters/cooling-fans.aspx

All the other "movable" air conditioning units need a pipe for the engine's heat that has to be connected out of a window.

For instance the Pinguino Delonghi, which is pretty common here in Italy.

I have the same concern about an apartment that I rent in Rome and where I can't actually place a stationary nor a movable unit.

Dyson seems to be the only reliable solution and, even if it isn't a real air conditioning system, it works pretty well.