Don't suggest google, I have tried.
GOODWILL!!! I got a pair of really nice fischer speakers for 3.99!
Personally this is one thing that I say forget the Internet. Go find some garage sales. Speakers are all over the place for dirt cheap.
Sometimes you find radios, tv's etc. at church sales, garage sales, thrift stores. Sometimes they are only a couple of dollars. You get the speakers and lots of other parts if you're careful.
Go by the tv repair shop near you. Offer to sweep up in trade for a couple of speakers.
Walk the streets on trash day.
There are lots of places where you can get stuff you need for free or verrry cheaply. If it don't work most people toss it out and ignore all the good parts inside. That's a good thing for us!
Freecycle.Craigslist.Not a web site, but: your local dumpsters, especially around the college housing.