A buddy of mine and his wife bought one of those little notebook laptops from bestbuy and I belive it had microsoft word and excel and able to surf the net for 300 bucks or so, I think it was fairly inexpensive. But depending on what you want to do with your computer or the different type of software you want to run on it there could be a big price difference. If you are just doing basic, email, internet, etc... I think some sort of notebook laptop would be pretty good.
I also have another buddy that used to go on Tiger Directand he would find smoking deals on PC's... its worth a look