I looked for whole house audio "on the cheap" for a long time and there really isn't such at thing unless you DIY. For many years I ran my own low power FM transmitter but more recently I discovered a software product called Airfoil which does the trick. Well worth the $25 IHMO.
https://www.rogueamoeba.com/airfoil/
The source needs to be Mac or Windows but the "speakers" can be almost anything. It does a pretty good job of keeping all your "speakers" in sync so you can have the same audio playing in the living room, kitchen, basement, office, and bedroom without having them playing at slightly different times or having to crank the volume to make the living room heard in other parts of the house. I have noticed the audio stream "stretching/speeding up/slowing down" sometimes in order to keep the playback in one area synchronized with another. It's not a problem with wired connections but there is no such thing a reliable wifi; you are guaranteed interference, drop outs, packet loss, etc.and that's where the audio will drop out or act 'strange.' With a little bit of scripting and home automation, I can have the "speakers" closest to me turn on when I'm near and then turn off a few minutes after I go away. I've even been known to take an iPod and some powered speakers out to the back yard for a little music outdoors, all in sync with the speakers in the house and access to my entire audio collection. Now if only I could get it loud enough to mow the lawn without also inflicting my music taste on the entire neighbourhood :-) Wireless noise cancelling headphones perhaps? Anybody got a silent lawn mower that doesn't involve a whole body workout? :-)
Cheers, Dave.