You will probably have to spend more to get robust multiple room wireless functionality. There simply isn't the demand to warrant the lower price point you are requesting. Plus, the vast majority of wireless systems will not hold a candle to the sound quality of wired ones.
FWIW, Sonos just announced a new iPod dock. Worth a look perhaps, especially if you have a pair of speakers laying around.
I recently purchased an iSymphony W2C, but it seems that additional wireless speakers are no longer available. I was thinking of returning it and getting the iSymphony W5C, but found several lousy reviews on Costco.com, & besides, the sound from the W2C isn't great. I want to be able to dock my iPod in one location and have 3 total sets of wireless speakers in 3 adjacent rooms. I'm not a big TV or video person - I really just want decent quality sound, with ability to use a remote to control the volume of each speaker set individually. Is there something out there that's high quality under $1 K that will allow this? Bose's home audio systems are too expensive for my budget, and go beyond my needs. Thanks in advance for ideas, etc.