logitech offers good value for the money. while not the best speakers ever made they get the job done without breaking the bank. if you want true audiophile level speakers be prepared to spend more cash.
I have to second ssddx's recommendation. I've had my set of Logitech X-530 5.1 surround sound speakers for years and I still get complaints from my apartment complex neighbors. I think I spend about $70 back in 2005/2006.