AirPlay is Apple's method of sending media over Wi-Fi -- it works very well in our home and our music library is distributed over three Macs, an iPhone and an iPad. This allows us to get at any of that from any of the devices and stream it to the speakers we want. Setup is borderline trivial.
If you have some old bookshelf speakers gathering dust and use an iOS device and/or a Mac, Griffin makes a cute little amplifier that accepts a $99 AirPort Express for a plug and play stereo system (2.1 if you have a self powered woofer). Just the thing for a small room and a cheap way to make use of kit you already have.
If this appeals and you don't have the speakers, ask a friend or check on craigslist. Twenty dollars is probably a fair price for a pair of old Bose 201s or similar kit.
No price or availability, but if it is under $150 they'll sell more than a few.