av123.com sells some Rocket outdoor speakers that are excellent (in terms of sound quality). I've had them for a year and they show no signs of wear. Of course, I have them under an overhang (not where direct rain would hit). Placing them completely out in the elements will shorten their lifespan. Not sure what price range you want... these run >$100.
As for cabling, you need to get wire that is rated for outdoor and/or underground use. The signals are not high voltage so a conduit is not required (double check your local electric code).