I bought a Netgear 4-port router and I like it so far. The web based interface makes for a very quick and easy setup.
You can also buy routers with bells and whistles like firewalls, print servers, VPN, etc. Naturally the cost goes up when the features are added. For a bare-bones 4-port router, you can get one for less than $100. Occasionally I'll see one for less than $50 with rebate. Check out Doc's Deals for the latest router bargains.