Cripes! Can we stop with the blanket misinformation?
1. Speakers are (generally) speakers are (generally) speakers. You get what you pay for and there are tons out there which you may consider perfectly acceptable for 'background' music.
ie:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=300-402
That's Parts Express (if the link doesn't work) for $42.00 a pair for in-ceiling speakers that will work for 'background' music in places like bathrooms and hallways or dining rooms where the volume will be low and the acoustics may suck.
2. You can't just string a bunch of speakers together willy-nilly.
Your A/V receiver has a main zone designed for 8 ohm... maybe 4 ohm output on each channel of amplification. It likely has a zone 2 amplifier (maybe) designed for an 8 ohm load. That's it. You can't just put a bunch of speakers on the amplifier and expect it to work. You will need impedence matching volume controls or a speaker selector - at the very least.
3. You can very much get top shelf in-wall speakers that will match some very good floor standing speakers on the market, but they will carry a price which matches those good floor standing speakers as well - if not costing more.
www.speakercraft.com and
www.sonance.com are two prime examples of companies which make in-walls which can blow away a lot of floor standing models out there, including motorized in-ceiling models.
If going whole house audio, with a bunch of speakers (which I strongly recommend!) then get a decent outboard amp... at the very least, something like this:
http://cgi.ebay.com/New-Audiosource-AMP-200-200-Watt-Power-Amplifier_W0QQitemZ310025457592QQihZ021QQcategoryZ39783QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
It will take the work load off your receiver and will give you enough power to run a bunch of speakers at once.
Better yet, is a true multi-channel amplifier like this:
http://cgi.ebay.com/Niles-SI-1230-12-Channel-Multi-Zone-Amplifier_W0QQitemZ290207631103QQihZ019QQcategoryZ14981QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
Which can independently power each pair of speakers you put around your home.
If it's a new home and you are able to run all the wiring now, I would think and plan a lot deeper than 'what cheap speakers can I use?' and would focus on - how many rooms can I wire? Can I get control to all the rooms? What about conduit? Independent zoning and control?
There's so much cool stuff you can do BEFORE the drywall goes up it's amazing, and it's all about planning and thinking about how you want things setup.
